<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2019 Workiva-->
<!--r:d797af35-25fa-49fe-b3f4-0d951c0b0d52,g:c1319243-2b25-48ff-80c3-a3394723d824-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.amkor.com/role/Cover" xlink:type="simple" xlink:href="amkr-20190930.xsd#Cover"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/Cover" xlink:type="extended" id="i4fbb8cd598c644eeac52810f4c1f6c11_c963c267-6394-40b4-907a-5de1e4a83445"/>
  <link:roleRef roleURI="http://www.amkor.com/role/ConsolidatedStatementsofIncomeUnaudited" xlink:type="simple" xlink:href="amkr-20190930.xsd#ConsolidatedStatementsofIncomeUnaudited"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/ConsolidatedStatementsofIncomeUnaudited" xlink:type="extended" id="i051d047d30d342a6859f5c9860cfdbb6_13443eb6-066e-4c58-bb88-4b8cd26ff09e"/>
  <link:roleRef roleURI="http://www.amkor.com/role/ConsolidatedStatementsofComprehensiveIncomeUnaudited" xlink:type="simple" xlink:href="amkr-20190930.xsd#ConsolidatedStatementsofComprehensiveIncomeUnaudited"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/ConsolidatedStatementsofComprehensiveIncomeUnaudited" xlink:type="extended" id="i171101f9bcd74dfe84934926aa9e35d1_b0064cf3-1a51-480c-86d2-bc3356d8e5cd"/>
  <link:roleRef roleURI="http://www.amkor.com/role/ConsolidatedBalanceSheetsUnaudited" xlink:type="simple" xlink:href="amkr-20190930.xsd#ConsolidatedBalanceSheetsUnaudited"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/ConsolidatedBalanceSheetsUnaudited" xlink:type="extended" id="if587e0eeb5434e66a0e0f096ab5d0312_28e2be1a-1c87-4145-8b28-32acecdbb58b"/>
  <link:roleRef roleURI="http://www.amkor.com/role/ConsolidatedBalanceSheetsUnauditedParenthetical" xlink:type="simple" xlink:href="amkr-20190930.xsd#ConsolidatedBalanceSheetsUnauditedParenthetical"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/ConsolidatedBalanceSheetsUnauditedParenthetical" xlink:type="extended" id="i296e1b327ff44fb5bf1d908c0f58b5df_2aac889c-3b25-45e6-b90e-9a886a24dee4"/>
  <link:roleRef roleURI="http://www.amkor.com/role/ConsolidatedStatementsofStockholdersEquityUnaudited" xlink:type="simple" xlink:href="amkr-20190930.xsd#ConsolidatedStatementsofStockholdersEquityUnaudited"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/ConsolidatedStatementsofStockholdersEquityUnaudited" xlink:type="extended" id="i332d230333fa4c30bcc4d01034d268ba_2c42b732-6edb-4af5-8898-426c13cc6665">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_2e6d98de-8f00-4225-8cdf-29301316e371" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d917b653-f1be-477b-8270-53bda994d3b4" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2e6d98de-8f00-4225-8cdf-29301316e371" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d917b653-f1be-477b-8270-53bda994d3b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_3c5e84a8-96bb-4bd7-ab1d-7eed77b5be48" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d917b653-f1be-477b-8270-53bda994d3b4" xlink:to="loc_us-gaap_CommonStockSharesIssued_3c5e84a8-96bb-4bd7-ab1d-7eed77b5be48" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockShares_9c164e1e-920d-4ffb-b7bb-7c2f6e39d4bc" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d917b653-f1be-477b-8270-53bda994d3b4" xlink:to="loc_us-gaap_TreasuryStockShares_9c164e1e-920d-4ffb-b7bb-7c2f6e39d4bc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_d2e80049-4f21-4aaf-bc14-22bbd84aa245" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d917b653-f1be-477b-8270-53bda994d3b4" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_d2e80049-4f21-4aaf-bc14-22bbd84aa245" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_536d32ee-66de-455f-93f3-88f02b4114f5" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d917b653-f1be-477b-8270-53bda994d3b4" xlink:to="loc_us-gaap_ProfitLoss_536d32ee-66de-455f-93f3-88f02b4114f5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_936f16d2-5507-4c12-9b46-2700ac09e117" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d917b653-f1be-477b-8270-53bda994d3b4" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_936f16d2-5507-4c12-9b46-2700ac09e117" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_3d62a6bb-e9b9-464c-8175-47c4b05cd70a" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d917b653-f1be-477b-8270-53bda994d3b4" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_3d62a6bb-e9b9-464c-8175-47c4b05cd70a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_646586f2-e7cb-4cab-8259-a2d9980f32c7" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d917b653-f1be-477b-8270-53bda994d3b4" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_646586f2-e7cb-4cab-8259-a2d9980f32c7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_ff4ca853-f77b-4d7a-8f29-ae2e3153711a" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d917b653-f1be-477b-8270-53bda994d3b4" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_ff4ca853-f77b-4d7a-8f29-ae2e3153711a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_fa3ac7ce-77f0-482b-9fce-ae93abcfd2ae" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d917b653-f1be-477b-8270-53bda994d3b4" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_fa3ac7ce-77f0-482b-9fce-ae93abcfd2ae" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_1bb67047-893a-4dc1-99e8-fb19a133ee56" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d917b653-f1be-477b-8270-53bda994d3b4" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_1bb67047-893a-4dc1-99e8-fb19a133ee56" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_1699e909-3d86-46f0-a7ec-01a70f2df630" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_d917b653-f1be-477b-8270-53bda994d3b4" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_1699e909-3d86-46f0-a7ec-01a70f2df630" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_c4837ff1-f1e7-4d51-b4fc-6bc6dd6ffa29" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockShares_04b97ba6-6fee-4dc8-8378-4f3016bada12" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockShares"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_3fdccce0-e049-4c61-bd4b-c51662a32b21" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_d15e0556-9fb6-4c64-9a88-a83ec0f09e6d" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_2e6d98de-8f00-4225-8cdf-29301316e371" xlink:to="loc_us-gaap_StatementTable_d15e0556-9fb6-4c64-9a88-a83ec0f09e6d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_a115f947-079c-46bc-a324-29fb00aea64e" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_d15e0556-9fb6-4c64-9a88-a83ec0f09e6d" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_a115f947-079c-46bc-a324-29fb00aea64e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_a115f947-079c-46bc-a324-29fb00aea64e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_a115f947-079c-46bc-a324-29fb00aea64e" xlink:to="loc_us-gaap_EquityComponentDomain_a115f947-079c-46bc-a324-29fb00aea64e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_bfeadfb8-fe98-4f2d-8a6c-c0c8d05e3c96" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_a115f947-079c-46bc-a324-29fb00aea64e" xlink:to="loc_us-gaap_EquityComponentDomain_bfeadfb8-fe98-4f2d-8a6c-c0c8d05e3c96" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParentMember_07a5e98c-2aff-4a11-b46f-45524e52b053" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_bfeadfb8-fe98-4f2d-8a6c-c0c8d05e3c96" xlink:to="loc_us-gaap_ParentMember_07a5e98c-2aff-4a11-b46f-45524e52b053" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_6f5f9ecc-c2cd-470b-97e0-471cf05750a1" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_07a5e98c-2aff-4a11-b46f-45524e52b053" xlink:to="loc_us-gaap_CommonStockMember_6f5f9ecc-c2cd-470b-97e0-471cf05750a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_77872c4c-ad4a-4c01-9ebe-885f048dabe0" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_07a5e98c-2aff-4a11-b46f-45524e52b053" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_77872c4c-ad4a-4c01-9ebe-885f048dabe0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_4aa75165-f81f-4089-ae79-e3e937e92046" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_07a5e98c-2aff-4a11-b46f-45524e52b053" xlink:to="loc_us-gaap_RetainedEarningsMember_4aa75165-f81f-4089-ae79-e3e937e92046" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_bc74ac9b-8213-4734-b5bc-d0347791429e" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_07a5e98c-2aff-4a11-b46f-45524e52b053" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_bc74ac9b-8213-4734-b5bc-d0347791429e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockMember_c52926e2-0348-40bd-8067-a395b3186139" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_07a5e98c-2aff-4a11-b46f-45524e52b053" xlink:to="loc_us-gaap_TreasuryStockMember_c52926e2-0348-40bd-8067-a395b3186139" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_ba5e64fe-59dd-4660-b056-cfbd452849b3" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_bfeadfb8-fe98-4f2d-8a6c-c0c8d05e3c96" xlink:to="loc_us-gaap_NoncontrollingInterestMember_ba5e64fe-59dd-4660-b056-cfbd452849b3" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.amkor.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited" xlink:type="simple" xlink:href="amkr-20190930.xsd#CondensedConsolidatedStatementsofCashFlowsUnaudited"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited" xlink:type="extended" id="i04406acec42b4a788c7222bc0dffa359_bae952bb-65bf-4370-b5b6-bb9b351907ce"/>
  <link:roleRef roleURI="http://www.amkor.com/role/InterimFinancialStatements" xlink:type="simple" xlink:href="amkr-20190930.xsd#InterimFinancialStatements"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/InterimFinancialStatements" xlink:type="extended" id="i2b1ff9db81214a54ae239467cc38ac45_76a105cb-894d-4b4b-8c55-1de7a53d3bbf"/>
  <link:roleRef roleURI="http://www.amkor.com/role/InterimFinancialStatementsPolicies" xlink:type="simple" xlink:href="amkr-20190930.xsd#InterimFinancialStatementsPolicies"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/InterimFinancialStatementsPolicies" xlink:type="extended" id="ia8a085152eb943b896f3417debf8765d_6e019862-abb9-4df7-9a52-4c19dfe8b02d"/>
  <link:roleRef roleURI="http://www.amkor.com/role/InterimFinancialStatementsDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#InterimFinancialStatementsDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/InterimFinancialStatementsDetails" xlink:type="extended" id="ida3dca45bac4407ca4a6d7f5a9fe74e5_20694082-b8c1-4e95-8952-0f3a9b917d42"/>
  <link:roleRef roleURI="http://www.amkor.com/role/NewAccountingStandards" xlink:type="simple" xlink:href="amkr-20190930.xsd#NewAccountingStandards"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/NewAccountingStandards" xlink:type="extended" id="ia70ce170178b4ae2bc69eabbccc98fe3_d6c8f4e2-4e1e-41d0-beb9-803c93f4c5a9"/>
  <link:roleRef roleURI="http://www.amkor.com/role/NetSalesbyProductGroupandEndMarket" xlink:type="simple" xlink:href="amkr-20190930.xsd#NetSalesbyProductGroupandEndMarket"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/NetSalesbyProductGroupandEndMarket" xlink:type="extended" id="i7b27886cfb7446f0828827c4afb56552_0f7e46eb-e1e3-4746-9f77-6b64414cbc89"/>
  <link:roleRef roleURI="http://www.amkor.com/role/NetSalesbyProductGroupandEndMarketTables" xlink:type="simple" xlink:href="amkr-20190930.xsd#NetSalesbyProductGroupandEndMarketTables"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/NetSalesbyProductGroupandEndMarketTables" xlink:type="extended" id="i36189a992abb41d887513c9f7665deff_e7721d9f-533b-4f1f-a9a7-341c60bb2d84"/>
  <link:roleRef roleURI="http://www.amkor.com/role/NetSalesbyProductGroupandEndMarketProductGroupDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#NetSalesbyProductGroupandEndMarketProductGroupDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/NetSalesbyProductGroupandEndMarketProductGroupDetails" xlink:type="extended" id="ie93dec7e39bf4bd78d72ad485c65de74_96b136ed-30c8-4024-bac2-000d8fe0a282">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_9b25266e-76ce-4b2c-9bdf-34811bfda6cd" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_daf5b5a9-2733-4792-8c6c-fcb16034fd8c" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_9b25266e-76ce-4b2c-9bdf-34811bfda6cd" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_daf5b5a9-2733-4792-8c6c-fcb16034fd8c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_8f339f46-6db8-455f-9e32-0d828edca4ea" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_9b25266e-76ce-4b2c-9bdf-34811bfda6cd" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_8f339f46-6db8-455f-9e32-0d828edca4ea" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_56651066-e710-43d3-a016-862044a2dd00" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_8f339f46-6db8-455f-9e32-0d828edca4ea" xlink:to="loc_srt_ProductOrServiceAxis_56651066-e710-43d3-a016-862044a2dd00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_56651066-e710-43d3-a016-862044a2dd00_default" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_56651066-e710-43d3-a016-862044a2dd00" xlink:to="loc_srt_ProductsAndServicesDomain_56651066-e710-43d3-a016-862044a2dd00_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_f44a517d-6e60-4f59-9286-350ba575aaf6" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_56651066-e710-43d3-a016-862044a2dd00" xlink:to="loc_srt_ProductsAndServicesDomain_f44a517d-6e60-4f59-9286-350ba575aaf6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_AdvancedProductsMember_eedde05c-bab1-49e5-b9c5-018de2e9d890" xlink:href="amkr-20190930.xsd#amkr_AdvancedProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f44a517d-6e60-4f59-9286-350ba575aaf6" xlink:to="loc_amkr_AdvancedProductsMember_eedde05c-bab1-49e5-b9c5-018de2e9d890" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_MainstreamProductsMember_adeaba29-4b7d-4393-8ed0-a925bf6607fa" xlink:href="amkr-20190930.xsd#amkr_MainstreamProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f44a517d-6e60-4f59-9286-350ba575aaf6" xlink:to="loc_amkr_MainstreamProductsMember_adeaba29-4b7d-4393-8ed0-a925bf6607fa" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.amkor.com/role/NetSalesbyProductGroupandEndMarketEndMarketDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#NetSalesbyProductGroupandEndMarketEndMarketDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/NetSalesbyProductGroupandEndMarketEndMarketDetails" xlink:type="extended" id="ib675b7a99da94875a5074b73a69c91f2_3211a572-1e08-4fe3-b457-e47fc8a9c3bd">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_227b84a0-129c-45bb-bd63-fd0ac6dc61f3" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_39c996a8-e58c-4fcf-bb6c-d800f1d8a1e2" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_227b84a0-129c-45bb-bd63-fd0ac6dc61f3" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_39c996a8-e58c-4fcf-bb6c-d800f1d8a1e2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_f4e5038f-4a53-423c-b90a-3581d0fe0c3b" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_227b84a0-129c-45bb-bd63-fd0ac6dc61f3" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_f4e5038f-4a53-423c-b90a-3581d0fe0c3b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_a1dce706-87a0-47a0-996e-3b7428ecfa3d" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_f4e5038f-4a53-423c-b90a-3581d0fe0c3b" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_a1dce706-87a0-47a0-996e-3b7428ecfa3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_a1dce706-87a0-47a0-996e-3b7428ecfa3d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_a1dce706-87a0-47a0-996e-3b7428ecfa3d" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_a1dce706-87a0-47a0-996e-3b7428ecfa3d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_4301a6da-a7e0-4846-9e51-2d7689880adf" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_a1dce706-87a0-47a0-996e-3b7428ecfa3d" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_4301a6da-a7e0-4846-9e51-2d7689880adf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_a52ee6ba-2368-461f-80dd-51b8106fd501" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_4301a6da-a7e0-4846-9e51-2d7689880adf" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_a52ee6ba-2368-461f-80dd-51b8106fd501" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_b6962a80-c52d-47b4-a9b3-4d081cb26f92" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_f4e5038f-4a53-423c-b90a-3581d0fe0c3b" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_b6962a80-c52d-47b4-a9b3-4d081cb26f92" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_b6962a80-c52d-47b4-a9b3-4d081cb26f92_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_b6962a80-c52d-47b4-a9b3-4d081cb26f92" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_b6962a80-c52d-47b4-a9b3-4d081cb26f92_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_0248e11f-f553-4f09-9f26-e19e61b63be4" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_b6962a80-c52d-47b4-a9b3-4d081cb26f92" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_0248e11f-f553-4f09-9f26-e19e61b63be4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_DistributionChannelConcentrationRiskMember_26ed0688-28a8-48bd-9c18-e13be13021a0" xlink:href="amkr-20190930.xsd#amkr_DistributionChannelConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_0248e11f-f553-4f09-9f26-e19e61b63be4" xlink:to="loc_amkr_DistributionChannelConcentrationRiskMember_26ed0688-28a8-48bd-9c18-e13be13021a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelAxis_3c122fc1-1dfe-47f2-9081-f52065df4184" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_f4e5038f-4a53-423c-b90a-3581d0fe0c3b" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelAxis_3c122fc1-1dfe-47f2-9081-f52065df4184" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_3c122fc1-1dfe-47f2-9081-f52065df4184_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_3c122fc1-1dfe-47f2-9081-f52065df4184" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_3c122fc1-1dfe-47f2-9081-f52065df4184_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_ae546988-fd71-4468-ab7e-ac7e445de887" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_3c122fc1-1dfe-47f2-9081-f52065df4184" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_ae546988-fd71-4468-ab7e-ac7e445de887" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_SalesChannelCommunicationsMember_6e05d3cf-b207-42f2-bea4-0186e9547fc5" xlink:href="amkr-20190930.xsd#amkr_SalesChannelCommunicationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_ae546988-fd71-4468-ab7e-ac7e445de887" xlink:to="loc_amkr_SalesChannelCommunicationsMember_6e05d3cf-b207-42f2-bea4-0186e9547fc5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_SalesChannelAutomotiveIndustrialAndOtherMember_4e900ab0-bff9-4eb5-9afa-a0ad8e0635c6" xlink:href="amkr-20190930.xsd#amkr_SalesChannelAutomotiveIndustrialAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_ae546988-fd71-4468-ab7e-ac7e445de887" xlink:to="loc_amkr_SalesChannelAutomotiveIndustrialAndOtherMember_4e900ab0-bff9-4eb5-9afa-a0ad8e0635c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_SalesChannelComputingMember_ddd8b877-88d8-48d4-92ce-a76673a48f64" xlink:href="amkr-20190930.xsd#amkr_SalesChannelComputingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_ae546988-fd71-4468-ab7e-ac7e445de887" xlink:to="loc_amkr_SalesChannelComputingMember_ddd8b877-88d8-48d4-92ce-a76673a48f64" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesChannelDirectlyToConsumerMember_e0f76c23-bf60-487c-b199-4f112fe92656" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SalesChannelDirectlyToConsumerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_ae546988-fd71-4468-ab7e-ac7e445de887" xlink:to="loc_us-gaap_SalesChannelDirectlyToConsumerMember_e0f76c23-bf60-487c-b199-4f112fe92656" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.amkor.com/role/OtherIncomeandExpense" xlink:type="simple" xlink:href="amkr-20190930.xsd#OtherIncomeandExpense"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/OtherIncomeandExpense" xlink:type="extended" id="i509a0091d9324564a328d6b2fca57299_c0fe64cc-192e-4bb5-9138-7f742ad7b714"/>
  <link:roleRef roleURI="http://www.amkor.com/role/OtherIncomeandExpenseTables" xlink:type="simple" xlink:href="amkr-20190930.xsd#OtherIncomeandExpenseTables"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/OtherIncomeandExpenseTables" xlink:type="extended" id="i48e07960a3454c1fa6e47cf03ea0adc6_840cac6a-e028-447e-aeab-c4683e4305a5"/>
  <link:roleRef roleURI="http://www.amkor.com/role/OtherIncomeandExpenseDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#OtherIncomeandExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/OtherIncomeandExpenseDetails" xlink:type="extended" id="ibbfbefa5601e4b6ba07f5e4bf2e8d4b3_05b9a318-52e6-4960-9c54-b26d1e615a39"/>
  <link:roleRef roleURI="http://www.amkor.com/role/IncomeTaxes" xlink:type="simple" xlink:href="amkr-20190930.xsd#IncomeTaxes"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/IncomeTaxes" xlink:type="extended" id="i3692c43c9ab3433581e4db0fe0d8dc99_d87abf36-eb47-4972-8f88-28285eaf8032"/>
  <link:roleRef roleURI="http://www.amkor.com/role/IncomeTaxesDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#IncomeTaxesDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/IncomeTaxesDetails" xlink:type="extended" id="i9994ef8f0a334fd3940623d25b96e7ec_0f22d0cb-e46b-4631-b20f-32da2e6977ea"/>
  <link:roleRef roleURI="http://www.amkor.com/role/EarningsPerShare" xlink:type="simple" xlink:href="amkr-20190930.xsd#EarningsPerShare"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/EarningsPerShare" xlink:type="extended" id="if981bfeeec3e49038ffe1e03c88471ce_8830427a-7374-4d7c-b31f-7d5384f7a84d"/>
  <link:roleRef roleURI="http://www.amkor.com/role/EarningsPerShareTables" xlink:type="simple" xlink:href="amkr-20190930.xsd#EarningsPerShareTables"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/EarningsPerShareTables" xlink:type="extended" id="i689ddf90d4c84028a09c3016a8596367_339214fe-3011-485c-a9b1-2784cdeca9e9"/>
  <link:roleRef roleURI="http://www.amkor.com/role/EarningsPerShareComputationofBasicandDilutedEPSDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#EarningsPerShareComputationofBasicandDilutedEPSDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/EarningsPerShareComputationofBasicandDilutedEPSDetails" xlink:type="extended" id="i906111df0baf4a4f9f42c701e6e667dd_6399e42e-1581-4772-9ca1-06b6986dc0eb"/>
  <link:roleRef roleURI="http://www.amkor.com/role/EarningsPerSharePotentialSharesofCommonStockExcludedfromDilutedEPSDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#EarningsPerSharePotentialSharesofCommonStockExcludedfromDilutedEPSDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/EarningsPerSharePotentialSharesofCommonStockExcludedfromDilutedEPSDetails" xlink:type="extended" id="i7dc90cb411a445d8aaa74e7ab286ffaf_45dbf4c0-5027-40d4-a37e-b5312d0dfd85">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_a53e0034-e274-4e0e-9604-392f3ba0befa" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_c7eec60c-ceee-4d3c-82a5-0d83a51c3d5c" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_a53e0034-e274-4e0e-9604-392f3ba0befa" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_c7eec60c-ceee-4d3c-82a5-0d83a51c3d5c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_89bbc77e-01bf-4967-a7e0-e24144b72422" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_a53e0034-e274-4e0e-9604-392f3ba0befa" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_89bbc77e-01bf-4967-a7e0-e24144b72422" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_7b2138cd-ce03-4164-8097-1f130c709b02" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_89bbc77e-01bf-4967-a7e0-e24144b72422" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_7b2138cd-ce03-4164-8097-1f130c709b02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_7b2138cd-ce03-4164-8097-1f130c709b02_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_7b2138cd-ce03-4164-8097-1f130c709b02" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_7b2138cd-ce03-4164-8097-1f130c709b02_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_ca5bca20-bbb2-48bf-99e7-144b48b89152" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_7b2138cd-ce03-4164-8097-1f130c709b02" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_ca5bca20-bbb2-48bf-99e7-144b48b89152" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_StockOptionsAndRestrictedSharesMember_c1b7fc91-958f-4118-9147-e0052f368162" xlink:href="amkr-20190930.xsd#amkr_StockOptionsAndRestrictedSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_ca5bca20-bbb2-48bf-99e7-144b48b89152" xlink:to="loc_amkr_StockOptionsAndRestrictedSharesMember_c1b7fc91-958f-4118-9147-e0052f368162" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.amkor.com/role/AccumulatedOtherComprehensiveIncomeLoss" xlink:type="simple" xlink:href="amkr-20190930.xsd#AccumulatedOtherComprehensiveIncomeLoss"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/AccumulatedOtherComprehensiveIncomeLoss" xlink:type="extended" id="i31ae4f8f42bb45cf945f538f05caea01_6337fcff-9e6b-4bd4-91bb-7fc58d7d36ff"/>
  <link:roleRef roleURI="http://www.amkor.com/role/AccumulatedOtherComprehensiveIncomeLossTables" xlink:type="simple" xlink:href="amkr-20190930.xsd#AccumulatedOtherComprehensiveIncomeLossTables"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/AccumulatedOtherComprehensiveIncomeLossTables" xlink:type="extended" id="ic6bbc3112ff24b90a3596da292488fc7_1e0b3c20-1c00-4ff6-be8c-2b8ad0a1347b"/>
  <link:roleRef roleURI="http://www.amkor.com/role/AccumulatedOtherComprehensiveIncomeLossDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#AccumulatedOtherComprehensiveIncomeLossDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/AccumulatedOtherComprehensiveIncomeLossDetails" xlink:type="extended" id="i41150b1d04b34d4f8e1111211c388e2e_c6f1f9d7-c1a6-4cf6-8d51-5df777818792">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_1f7226f3-5d05-45b5-8eb5-824497680b19" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_7b426457-0124-4c9e-868a-a8a719c4a1d0" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_1f7226f3-5d05-45b5-8eb5-824497680b19" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_7b426457-0124-4c9e-868a-a8a719c4a1d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_a35d871b-b18e-409b-8500-1386b856070f" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_7b426457-0124-4c9e-868a-a8a719c4a1d0" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_a35d871b-b18e-409b-8500-1386b856070f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_95ae3530-19fb-40ad-b66e-1d1996d714fd" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_7b426457-0124-4c9e-868a-a8a719c4a1d0" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_95ae3530-19fb-40ad-b66e-1d1996d714fd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_59416f06-3769-460c-991e-4b905e455a6c" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_7b426457-0124-4c9e-868a-a8a719c4a1d0" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_59416f06-3769-460c-991e-4b905e455a6c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_0eba3a20-e52d-4603-b21f-7a0f93181caf" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_7b426457-0124-4c9e-868a-a8a719c4a1d0" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_0eba3a20-e52d-4603-b21f-7a0f93181caf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_0ee3a465-c84c-4176-9a72-274df6993fad" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_48f4c3ad-e1e6-4b7e-98d0-f7b0bd4593f8" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_1f7226f3-5d05-45b5-8eb5-824497680b19" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_48f4c3ad-e1e6-4b7e-98d0-f7b0bd4593f8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_b6b338e9-5942-4de4-9f88-c4af186927da" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_48f4c3ad-e1e6-4b7e-98d0-f7b0bd4593f8" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_b6b338e9-5942-4de4-9f88-c4af186927da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_b6b338e9-5942-4de4-9f88-c4af186927da_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_b6b338e9-5942-4de4-9f88-c4af186927da" xlink:to="loc_us-gaap_EquityComponentDomain_b6b338e9-5942-4de4-9f88-c4af186927da_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_7b885187-e79b-43ba-9fb9-12de70673d43" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_b6b338e9-5942-4de4-9f88-c4af186927da" xlink:to="loc_us-gaap_EquityComponentDomain_7b885187-e79b-43ba-9fb9-12de70673d43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember_1bcfee64-8a23-48d5-977a-4aa940d5e3e3" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_7b885187-e79b-43ba-9fb9-12de70673d43" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember_1bcfee64-8a23-48d5-977a-4aa940d5e3e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember_f3f8e214-ec87-4e49-91d8-1d636ef7f448" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_7b885187-e79b-43ba-9fb9-12de70673d43" xlink:to="loc_us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember_f3f8e214-ec87-4e49-91d8-1d636ef7f448" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_cc3646c0-c5d5-4516-bbed-d415cb12ea52" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_7b885187-e79b-43ba-9fb9-12de70673d43" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_cc3646c0-c5d5-4516-bbed-d415cb12ea52" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.amkor.com/role/FactoringofAccountsReceivable" xlink:type="simple" xlink:href="amkr-20190930.xsd#FactoringofAccountsReceivable"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/FactoringofAccountsReceivable" xlink:type="extended" id="ifc27399750f54790a687ac0bd4499b2a_89cd72c3-3433-4d8c-8c5e-3bc994ae41e8"/>
  <link:roleRef roleURI="http://www.amkor.com/role/FactoringofAccountsReceivableDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#FactoringofAccountsReceivableDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/FactoringofAccountsReceivableDetails" xlink:type="extended" id="i8839ae9038b9446bbe50a0e466559ac9_40f034a3-6ffe-4588-aec1-21ebe6dd9a61">
    <link:loc xlink:type="locator" xlink:label="loc_amkr_FactoringofAccountsReceivableLineItems_790b06f6-e7f3-4b06-aef2-ab8ff2820165" xlink:href="amkr-20190930.xsd#amkr_FactoringofAccountsReceivableLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_AccountsReceivableSoldwithoutRecourse_1aed8f8d-e8db-452d-bd79-925d2ab63fd1" xlink:href="amkr-20190930.xsd#amkr_AccountsReceivableSoldwithoutRecourse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_amkr_FactoringofAccountsReceivableLineItems_790b06f6-e7f3-4b06-aef2-ab8ff2820165" xlink:to="loc_amkr_AccountsReceivableSoldwithoutRecourse_1aed8f8d-e8db-452d-bd79-925d2ab63fd1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_FactoringofAccountsReceivableTable_3673861a-8291-49ea-b6e9-af37d9c7df4d" xlink:href="amkr-20190930.xsd#amkr_FactoringofAccountsReceivableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_amkr_FactoringofAccountsReceivableLineItems_790b06f6-e7f3-4b06-aef2-ab8ff2820165" xlink:to="loc_amkr_FactoringofAccountsReceivableTable_3673861a-8291-49ea-b6e9-af37d9c7df4d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_FactoringofAccountsReceivableAxis_b2e754c1-7b50-4426-aa18-923eb99c91c6" xlink:href="amkr-20190930.xsd#amkr_FactoringofAccountsReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_amkr_FactoringofAccountsReceivableTable_3673861a-8291-49ea-b6e9-af37d9c7df4d" xlink:to="loc_amkr_FactoringofAccountsReceivableAxis_b2e754c1-7b50-4426-aa18-923eb99c91c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_FactoringofAccountsReceivableDomain_b2e754c1-7b50-4426-aa18-923eb99c91c6_default" xlink:href="amkr-20190930.xsd#amkr_FactoringofAccountsReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_amkr_FactoringofAccountsReceivableAxis_b2e754c1-7b50-4426-aa18-923eb99c91c6" xlink:to="loc_amkr_FactoringofAccountsReceivableDomain_b2e754c1-7b50-4426-aa18-923eb99c91c6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_FactoringofAccountsReceivableDomain_2526a34a-09cf-44c4-a378-e2a8c8e4dc1a" xlink:href="amkr-20190930.xsd#amkr_FactoringofAccountsReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_amkr_FactoringofAccountsReceivableAxis_b2e754c1-7b50-4426-aa18-923eb99c91c6" xlink:to="loc_amkr_FactoringofAccountsReceivableDomain_2526a34a-09cf-44c4-a378-e2a8c8e4dc1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_TotalFactoredMember_7886084d-7b9c-4735-ad1e-ab277089d8d2" xlink:href="amkr-20190930.xsd#amkr_TotalFactoredMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_amkr_FactoringofAccountsReceivableDomain_2526a34a-09cf-44c4-a378-e2a8c8e4dc1a" xlink:to="loc_amkr_TotalFactoredMember_7886084d-7b9c-4735-ad1e-ab277089d8d2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_FactoringFeesMember_30c9cded-14c5-42dd-9abe-983545286324" xlink:href="amkr-20190930.xsd#amkr_FactoringFeesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_amkr_FactoringofAccountsReceivableDomain_2526a34a-09cf-44c4-a378-e2a8c8e4dc1a" xlink:to="loc_amkr_FactoringFeesMember_30c9cded-14c5-42dd-9abe-983545286324" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.amkor.com/role/PropertyPlantandEquipment" xlink:type="simple" xlink:href="amkr-20190930.xsd#PropertyPlantandEquipment"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/PropertyPlantandEquipment" xlink:type="extended" id="ibdbb88017ab74108a1131fd651c9d042_99dbaade-4a5e-4e8a-a6ff-5963f7aed7ad"/>
  <link:roleRef roleURI="http://www.amkor.com/role/PropertyPlantandEquipmentTables" xlink:type="simple" xlink:href="amkr-20190930.xsd#PropertyPlantandEquipmentTables"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/PropertyPlantandEquipmentTables" xlink:type="extended" id="if88523b765674ca8b1642fde03bfbeec_4a182b0c-0c48-4c2f-9871-62b7d99d7ed4"/>
  <link:roleRef roleURI="http://www.amkor.com/role/PropertyPlantandEquipmentSummaryofPropertyPlantandEquipmentDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#PropertyPlantandEquipmentSummaryofPropertyPlantandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/PropertyPlantandEquipmentSummaryofPropertyPlantandEquipmentDetails" xlink:type="extended" id="i6f22b90a43114420bd0c1cf36e3d4ba1_2b823d40-d17d-4c2d-bfb2-ec916cf1934f">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_94d34739-56da-46dd-b6c3-55ffc25f5f27" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_5efee4f3-0022-4427-b0f6-7deb3cfeeec2" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_94d34739-56da-46dd-b6c3-55ffc25f5f27" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_5efee4f3-0022-4427-b0f6-7deb3cfeeec2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_5c3fa3e3-f541-4d4d-8612-873b55e9ac62" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_94d34739-56da-46dd-b6c3-55ffc25f5f27" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_5c3fa3e3-f541-4d4d-8612-873b55e9ac62" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_868fc86a-7f2e-45a0-8228-47d6a36cf764" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_94d34739-56da-46dd-b6c3-55ffc25f5f27" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_868fc86a-7f2e-45a0-8228-47d6a36cf764" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_2de38b92-67b7-48ba-a3ca-280e43ad7098" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_94d34739-56da-46dd-b6c3-55ffc25f5f27" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_2de38b92-67b7-48ba-a3ca-280e43ad7098" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e1d4609d-7ee2-4ebe-8bbb-acdfc6f9b883" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_2de38b92-67b7-48ba-a3ca-280e43ad7098" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e1d4609d-7ee2-4ebe-8bbb-acdfc6f9b883" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e1d4609d-7ee2-4ebe-8bbb-acdfc6f9b883_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e1d4609d-7ee2-4ebe-8bbb-acdfc6f9b883" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e1d4609d-7ee2-4ebe-8bbb-acdfc6f9b883_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2174e610-cc4e-4f6e-8217-627d1db6b713" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e1d4609d-7ee2-4ebe-8bbb-acdfc6f9b883" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2174e610-cc4e-4f6e-8217-627d1db6b713" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandMember_bf78786b-c49c-4ce8-acf6-b2973c8fa06c" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LandMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2174e610-cc4e-4f6e-8217-627d1db6b713" xlink:to="loc_us-gaap_LandMember_bf78786b-c49c-4ce8-acf6-b2973c8fa06c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UseRightsMember_3f5d56ae-ad32-477b-b74b-aa3d054846ef" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UseRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2174e610-cc4e-4f6e-8217-627d1db6b713" xlink:to="loc_us-gaap_UseRightsMember_3f5d56ae-ad32-477b-b74b-aa3d054846ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingAndBuildingImprovementsMember_4a49fcf9-8e1e-4219-82b8-c91a461b19e1" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BuildingAndBuildingImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2174e610-cc4e-4f6e-8217-627d1db6b713" xlink:to="loc_us-gaap_BuildingAndBuildingImprovementsMember_4a49fcf9-8e1e-4219-82b8-c91a461b19e1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_7f5023e9-7c11-4ca3-909b-1cef2fe39840" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2174e610-cc4e-4f6e-8217-627d1db6b713" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_7f5023e9-7c11-4ca3-909b-1cef2fe39840" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_FinanceLeasedAssetsMember_ef6aba9a-0da2-4087-8a0a-a3f9713b8134" xlink:href="amkr-20190930.xsd#amkr_FinanceLeasedAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2174e610-cc4e-4f6e-8217-627d1db6b713" xlink:to="loc_amkr_FinanceLeasedAssetsMember_ef6aba9a-0da2-4087-8a0a-a3f9713b8134" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_SoftwareAndComputerEquipmentMember_b50ed460-32e7-4032-adb2-8e7a57cb4bec" xlink:href="amkr-20190930.xsd#amkr_SoftwareAndComputerEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2174e610-cc4e-4f6e-8217-627d1db6b713" xlink:to="loc_amkr_SoftwareAndComputerEquipmentMember_b50ed460-32e7-4032-adb2-8e7a57cb4bec" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_a631119c-a906-4378-b620-c48c0ca03160" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2174e610-cc4e-4f6e-8217-627d1db6b713" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_a631119c-a906-4378-b620-c48c0ca03160" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_be8a544c-fe4f-44d4-b3ea-7b8198752896" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_2174e610-cc4e-4f6e-8217-627d1db6b713" xlink:to="loc_us-gaap_ConstructionInProgressMember_be8a544c-fe4f-44d4-b3ea-7b8198752896" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.amkor.com/role/PropertyPlantandEquipmentSummaryofDepreciationExpenseDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#PropertyPlantandEquipmentSummaryofDepreciationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/PropertyPlantandEquipmentSummaryofDepreciationExpenseDetails" xlink:type="extended" id="i21c6f4204c424577a68b25cc3fc9846f_250c27ce-682b-4161-bc17-0c3f66ae1c69"/>
  <link:roleRef roleURI="http://www.amkor.com/role/Leases" xlink:type="simple" xlink:href="amkr-20190930.xsd#Leases"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/Leases" xlink:type="extended" id="i5a6e06d265b04241a22fb3b3da4685f5_70b25bf9-341f-4de2-aedd-35afd413de5f"/>
  <link:roleRef roleURI="http://www.amkor.com/role/LeasesTables" xlink:type="simple" xlink:href="amkr-20190930.xsd#LeasesTables"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/LeasesTables" xlink:type="extended" id="i2d48e523d8fb46bcbff7670059a44da7_6d1acf4c-4c2d-4912-b3df-5d78547e70f0"/>
  <link:roleRef roleURI="http://www.amkor.com/role/LeasesComponentsofLeaseExpenseDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#LeasesComponentsofLeaseExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/LeasesComponentsofLeaseExpenseDetails" xlink:type="extended" id="if847873c766245f99a367d9d7302801e_3cef5271-1050-4674-ad7d-5a5f9dfc7297">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_9b1c4651-1834-4bb8-8489-0aae9b3cd4bd" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_LeaseRemainingLeaseTerm_50715648-32b8-441d-93e1-4f9064833e6d" xlink:href="amkr-20190930.xsd#amkr_LeaseRemainingLeaseTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9b1c4651-1834-4bb8-8489-0aae9b3cd4bd" xlink:to="loc_amkr_LeaseRemainingLeaseTerm_50715648-32b8-441d-93e1-4f9064833e6d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseCost_32354aeb-d22d-4c9c-9a75-992f0f0c081f" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9b1c4651-1834-4bb8-8489-0aae9b3cd4bd" xlink:to="loc_us-gaap_OperatingLeaseCost_32354aeb-d22d-4c9c-9a75-992f0f0c081f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseCostAbstract_824822f6-5b48-4fd3-819c-7ae548bc8f77" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseCostAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9b1c4651-1834-4bb8-8489-0aae9b3cd4bd" xlink:to="loc_us-gaap_FinanceLeaseCostAbstract_824822f6-5b48-4fd3-819c-7ae548bc8f77" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_f27d3407-33b1-466c-91bc-999c2ec344e5" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseRightOfUseAssetAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinanceLeaseCostAbstract_824822f6-5b48-4fd3-819c-7ae548bc8f77" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_f27d3407-33b1-466c-91bc-999c2ec344e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseInterestExpense_a5f70a76-4067-4e6d-81ce-301fe2b6e4eb" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinanceLeaseCostAbstract_824822f6-5b48-4fd3-819c-7ae548bc8f77" xlink:to="loc_us-gaap_FinanceLeaseInterestExpense_a5f70a76-4067-4e6d-81ce-301fe2b6e4eb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_FinanceLeaseCost_9c0231d7-52ba-4ef2-ab7b-1c400e958daa" xlink:href="amkr-20190930.xsd#amkr_FinanceLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinanceLeaseCostAbstract_824822f6-5b48-4fd3-819c-7ae548bc8f77" xlink:to="loc_amkr_FinanceLeaseCost_9c0231d7-52ba-4ef2-ab7b-1c400e958daa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermLeaseCost_a6654e5a-a9ce-4b20-91ec-c27e13907490" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShortTermLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9b1c4651-1834-4bb8-8489-0aae9b3cd4bd" xlink:to="loc_us-gaap_ShortTermLeaseCost_a6654e5a-a9ce-4b20-91ec-c27e13907490" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableLeaseCost_df721a8c-5116-4584-9e18-a65b39aa7cff" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9b1c4651-1834-4bb8-8489-0aae9b3cd4bd" xlink:to="loc_us-gaap_VariableLeaseCost_df721a8c-5116-4584-9e18-a65b39aa7cff" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseCost_f29d1811-40eb-4643-9f9c-d59ca699a240" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9b1c4651-1834-4bb8-8489-0aae9b3cd4bd" xlink:to="loc_us-gaap_LeaseCost_f29d1811-40eb-4643-9f9c-d59ca699a240" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseAndRentalExpense_f3af65a3-87b9-4e4e-8abc-547a9b0be59d" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LeaseAndRentalExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9b1c4651-1834-4bb8-8489-0aae9b3cd4bd" xlink:to="loc_us-gaap_LeaseAndRentalExpense_f3af65a3-87b9-4e4e-8abc-547a9b0be59d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasePayments_cc2c2398-c009-4edb-bfd4-e86065a30477" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9b1c4651-1834-4bb8-8489-0aae9b3cd4bd" xlink:to="loc_us-gaap_OperatingLeasePayments_cc2c2398-c009-4edb-bfd4-e86065a30477" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseInterestPaymentOnLiability_5c3127af-1e53-41f0-b2eb-c1385e6d8edb" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseInterestPaymentOnLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9b1c4651-1834-4bb8-8489-0aae9b3cd4bd" xlink:to="loc_us-gaap_FinanceLeaseInterestPaymentOnLiability_5c3127af-1e53-41f0-b2eb-c1385e6d8edb" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeasePrincipalPayments_e53419ae-3bfc-46a9-88fe-7047823b224e" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeasePrincipalPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9b1c4651-1834-4bb8-8489-0aae9b3cd4bd" xlink:to="loc_us-gaap_FinanceLeasePrincipalPayments_e53419ae-3bfc-46a9-88fe-7047823b224e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_b1c7f6cc-bd7d-41f5-9d86-26a926e1738c" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9b1c4651-1834-4bb8-8489-0aae9b3cd4bd" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_b1c7f6cc-bd7d-41f5-9d86-26a926e1738c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1_c452c2a0-688d-432a-b2cf-74e9b65e9c6b" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9b1c4651-1834-4bb8-8489-0aae9b3cd4bd" xlink:to="loc_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1_c452c2a0-688d-432a-b2cf-74e9b65e9c6b" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_b3aa6954-962e-4c2d-ac15-1cfa8ff44b7f" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9b1c4651-1834-4bb8-8489-0aae9b3cd4bd" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_b3aa6954-962e-4c2d-ac15-1cfa8ff44b7f" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent_fe68d912-5251-4ebf-a9dc-9d753e03397d" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9b1c4651-1834-4bb8-8489-0aae9b3cd4bd" xlink:to="loc_us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent_fe68d912-5251-4ebf-a9dc-9d753e03397d" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_564c0ff6-1753-4ff5-bdff-716a12fc690d" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9b1c4651-1834-4bb8-8489-0aae9b3cd4bd" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_564c0ff6-1753-4ff5-bdff-716a12fc690d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_0cedec6b-290f-4a9b-b49d-cce541e9da5b" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_564c0ff6-1753-4ff5-bdff-716a12fc690d" xlink:to="loc_srt_RangeAxis_0cedec6b-290f-4a9b-b49d-cce541e9da5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_0cedec6b-290f-4a9b-b49d-cce541e9da5b_default" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_0cedec6b-290f-4a9b-b49d-cce541e9da5b" xlink:to="loc_srt_RangeMember_0cedec6b-290f-4a9b-b49d-cce541e9da5b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_1142cc2e-258c-4503-b49b-e298c5c009e2" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_0cedec6b-290f-4a9b-b49d-cce541e9da5b" xlink:to="loc_srt_RangeMember_1142cc2e-258c-4503-b49b-e298c5c009e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_967e2436-a893-45f6-b730-5647cac8d58b" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_1142cc2e-258c-4503-b49b-e298c5c009e2" xlink:to="loc_srt_MinimumMember_967e2436-a893-45f6-b730-5647cac8d58b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_8e56715f-1a31-471c-83dc-4bf66b297189" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_1142cc2e-258c-4503-b49b-e298c5c009e2" xlink:to="loc_srt_MaximumMember_8e56715f-1a31-471c-83dc-4bf66b297189" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.amkor.com/role/LeasesFutureMinimumLeasePaymentsDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#LeasesFutureMinimumLeasePaymentsDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/LeasesFutureMinimumLeasePaymentsDetails" xlink:type="extended" id="i64a28a4a564d46a6ab4e875b0d2da27d_90a9ca8c-f3b2-42cf-a1f8-b6f95ac75a78"/>
  <link:roleRef roleURI="http://www.amkor.com/role/AccruedExpenses" xlink:type="simple" xlink:href="amkr-20190930.xsd#AccruedExpenses"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/AccruedExpenses" xlink:type="extended" id="i0ac2c499d45740ad8fcaf265469cfed1_4cf6f377-dd24-41ac-94e0-0bbb5804acec"/>
  <link:roleRef roleURI="http://www.amkor.com/role/AccruedExpensesTables" xlink:type="simple" xlink:href="amkr-20190930.xsd#AccruedExpensesTables"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/AccruedExpensesTables" xlink:type="extended" id="id21ae343cec24e7f98ccf98082317449_a59505ab-60c4-45dc-a4b0-fe2e2eede7da"/>
  <link:roleRef roleURI="http://www.amkor.com/role/AccruedExpensesDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#AccruedExpensesDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/AccruedExpensesDetails" xlink:type="extended" id="i8230c90cb57448cbb910a8e149579a2f_26326e99-e3c4-4c23-907a-773ab2e10bdd"/>
  <link:roleRef roleURI="http://www.amkor.com/role/Debt" xlink:type="simple" xlink:href="amkr-20190930.xsd#Debt"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/Debt" xlink:type="extended" id="i87ddfc3a64304d369e5b0cda77da4170_c2ef164b-7888-4983-b6af-ed4dbbb72b19"/>
  <link:roleRef roleURI="http://www.amkor.com/role/DebtTables" xlink:type="simple" xlink:href="amkr-20190930.xsd#DebtTables"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/DebtTables" xlink:type="extended" id="i5fe1f27f8db54a539f59a8c4a7bdead9_a852bf45-4a7a-4be3-95c1-1ef09d08b7b3"/>
  <link:roleRef roleURI="http://www.amkor.com/role/DebtDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#DebtDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/DebtDetails" xlink:type="extended" id="iba92554595924d7e82a9d8ed9cbc47e3_aff800da-a201-41e2-91da-9f7a6f1e083e">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_cf131c9b-a883-4d11-bff9-3db9cd34311d" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_cf131c9b-a883-4d11-bff9-3db9cd34311d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_6770b5c1-df62-4ff6-9323-fde2b5569cf7" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_LongTermDebt_6770b5c1-df62-4ff6-9323-fde2b5569cf7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_c8361879-a678-4c7d-81a7-78b8eec4a16d" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_c8361879-a678-4c7d-81a7-78b8eec4a16d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_a78d7201-146e-4007-88cf-d2b7412b49d9" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_LongTermDebtCurrent_a78d7201-146e-4007-88cf-d2b7412b49d9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_876bbbcf-ae8c-4284-a70f-60cc9cfc9114" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_876bbbcf-ae8c-4284-a70f-60cc9cfc9114" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_92b47281-f809-43f7-b759-634a271829be" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_92b47281-f809-43f7-b759-634a271829be" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_a493515a-5db3-4de6-9b5d-3e96d8f9fb6a" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_a493515a-5db3-4de6-9b5d-3e96d8f9fb6a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_a7330ec2-e0e3-4c0e-b59a-325e48a9474a" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_a7330ec2-e0e3-4c0e-b59a-325e48a9474a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_547f249e-0dac-47b6-9a45-1e61f746c000" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_547f249e-0dac-47b6-9a45-1e61f746c000" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_496917be-bb5b-4c59-84a4-37ef82f34160" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_496917be-bb5b-4c59-84a4-37ef82f34160" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsGross_7d81982f-e539-42c2-8b21-2047d87d3ac0" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredFinanceCostsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_DeferredFinanceCostsGross_7d81982f-e539-42c2-8b21-2047d87d3ac0" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_DebtInstrumentIssuancePercentageofPar_6980a0d1-97a3-4288-882f-dfb85a110968" xlink:href="amkr-20190930.xsd#amkr_DebtInstrumentIssuancePercentageofPar"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_amkr_DebtInstrumentIssuancePercentageofPar_6980a0d1-97a3-4288-882f-dfb85a110968" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_4741a708-f979-4a83-883c-1eef2f1e5a7b" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_4741a708-f979-4a83-883c-1eef2f1e5a7b" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_8070f9ee-6be4-4e3d-b545-f5916ab3df2f" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_8070f9ee-6be4-4e3d-b545-f5916ab3df2f" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_a13fd573-3a5c-4022-9996-801d687f3546" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_a13fd573-3a5c-4022-9996-801d687f3546" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_DebtInstrumentNumberOfLoans_313e758d-69a7-4270-9990-0a7c4123af61" xlink:href="amkr-20190930.xsd#amkr_DebtInstrumentNumberOfLoans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_amkr_DebtInstrumentNumberOfLoans_313e758d-69a7-4270-9990-0a7c4123af61" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_13c6d227-777f-4ed4-90ae-644b041895af" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_13c6d227-777f-4ed4-90ae-644b041895af" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLinesOfCredit_9b1198c8-e45a-4592-8ec3-7136d324d7f3" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RepaymentsOfLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_RepaymentsOfLinesOfCredit_9b1198c8-e45a-4592-8ec3-7136d324d7f3" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_9489eeba-ae90-4733-a514-4c2228368b40" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_9489eeba-ae90-4733-a514-4c2228368b40" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_fdc3f518-994a-4dde-b48b-a927604ccb17" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_fdc3f518-994a-4dde-b48b-a927604ccb17" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtWeightedAverageInterestRate_25c67e40-08d8-4546-9c31-007cc4adb1c3" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_LongtermDebtWeightedAverageInterestRate_25c67e40-08d8-4546-9c31-007cc4adb1c3" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_575e0fa2-a602-4fe9-bb18-ea2bb38b9ba6" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_575e0fa2-a602-4fe9-bb18-ea2bb38b9ba6" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_116d9d73-eeb5-4839-ab63-760484ff942d" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentPeriodicPaymentPrincipal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_116d9d73-eeb5-4839-ab63-760484ff942d" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_c5898bf1-edda-4620-a03e-99ad15ddc83d" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_c5898bf1-edda-4620-a03e-99ad15ddc83d" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_e7fdc3ac-b1cd-4c83-879f-9ddff65d9001" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4dd2fbc4-4c86-4e8e-beb2-e4b3c70adbc4" xlink:to="loc_us-gaap_DebtInstrumentTable_e7fdc3ac-b1cd-4c83-879f-9ddff65d9001" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_6a6f91f6-fbf2-4106-a793-dfe102aa45dd" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_e7fdc3ac-b1cd-4c83-879f-9ddff65d9001" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_6a6f91f6-fbf2-4106-a793-dfe102aa45dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_6a6f91f6-fbf2-4106-a793-dfe102aa45dd_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_6a6f91f6-fbf2-4106-a793-dfe102aa45dd" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_6a6f91f6-fbf2-4106-a793-dfe102aa45dd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_aae430a6-a4e1-4337-9e53-72ac131fb6fb" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_6a6f91f6-fbf2-4106-a793-dfe102aa45dd" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_aae430a6-a4e1-4337-9e53-72ac131fb6fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_45a77460-6006-464f-a8f5-3f8adee3f004" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_aae430a6-a4e1-4337-9e53-72ac131fb6fb" xlink:to="loc_us-gaap_LineOfCreditMember_45a77460-6006-464f-a8f5-3f8adee3f004" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_7f00778c-33c6-4d51-bfe5-89efd3be7653" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_aae430a6-a4e1-4337-9e53-72ac131fb6fb" xlink:to="loc_us-gaap_SeniorNotesMember_7f00778c-33c6-4d51-bfe5-89efd3be7653" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_SubsidiaryTermLoansMember_13ea52d3-399b-4c83-91c0-940ecb83c35e" xlink:href="amkr-20190930.xsd#amkr_SubsidiaryTermLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_aae430a6-a4e1-4337-9e53-72ac131fb6fb" xlink:to="loc_amkr_SubsidiaryTermLoansMember_13ea52d3-399b-4c83-91c0-940ecb83c35e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_cdd5b6ff-55b1-4e43-b021-3d58c371c171" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_e7fdc3ac-b1cd-4c83-879f-9ddff65d9001" xlink:to="loc_us-gaap_DebtInstrumentAxis_cdd5b6ff-55b1-4e43-b021-3d58c371c171" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_cdd5b6ff-55b1-4e43-b021-3d58c371c171_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_cdd5b6ff-55b1-4e43-b021-3d58c371c171" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_cdd5b6ff-55b1-4e43-b021-3d58c371c171_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_cdd5b6ff-55b1-4e43-b021-3d58c371c171" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_SeniorNotesDueOctober2022Member_7edd390b-895b-48d9-84b8-bf2e48e7dfae" xlink:href="amkr-20190930.xsd#amkr_SeniorNotesDueOctober2022Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_SeniorNotesDueOctober2022Member_7edd390b-895b-48d9-84b8-bf2e48e7dfae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_SeniorNotesDueSeptember2027Member_dbb82ecc-ea3f-4a3a-b4a8-c5c8108f9a5c" xlink:href="amkr-20190930.xsd#amkr_SeniorNotesDueSeptember2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_SeniorNotesDueSeptember2027Member_dbb82ecc-ea3f-4a3a-b4a8-c5c8108f9a5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_RevolvingCreditFacilityDueOctober2019Member_8d2ed4d2-f04e-48bf-a0b3-d798cdbf12d0" xlink:href="amkr-20190930.xsd#amkr_RevolvingCreditFacilityDueOctober2019Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_RevolvingCreditFacilityDueOctober2019Member_8d2ed4d2-f04e-48bf-a0b3-d798cdbf12d0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_FixedRateTermLoanDueMay2020Member_bcf8ea53-36d5-4903-829c-8b1228c25f6c" xlink:href="amkr-20190930.xsd#amkr_FixedRateTermLoanDueMay2020Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_FixedRateTermLoanDueMay2020Member_bcf8ea53-36d5-4903-829c-8b1228c25f6c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_TermLoanDueJune2020Member_278f0b0a-a799-45d3-b7d1-defa0be23720" xlink:href="amkr-20190930.xsd#amkr_TermLoanDueJune2020Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_TermLoanDueJune2020Member_278f0b0a-a799-45d3-b7d1-defa0be23720" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_TermLoanDueJuly2022Member_379cb195-0e7e-49ef-8718-5ea2a1ef8caa" xlink:href="amkr-20190930.xsd#amkr_TermLoanDueJuly2022Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_TermLoanDueJuly2022Member_379cb195-0e7e-49ef-8718-5ea2a1ef8caa" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_TermLoanDueSeptember2022Member_8a595ac0-e652-405f-9355-f98256ea607a" xlink:href="amkr-20190930.xsd#amkr_TermLoanDueSeptember2022Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_TermLoanDueSeptember2022Member_8a595ac0-e652-405f-9355-f98256ea607a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_TermLoanDueDecember2023Member_db5ed387-4fb1-4c51-8e59-4b53e5db2a41" xlink:href="amkr-20190930.xsd#amkr_TermLoanDueDecember2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_TermLoanDueDecember2023Member_db5ed387-4fb1-4c51-8e59-4b53e5db2a41" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_TermLoanDueDecember2028Member_3d689f16-0185-4c2b-84db-646e6f985f62" xlink:href="amkr-20190930.xsd#amkr_TermLoanDueDecember2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_TermLoanDueDecember2028Member_3d689f16-0185-4c2b-84db-646e6f985f62" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_ShorttermtermloanvariablerateMember_9b5e8f64-4ea7-49d3-9602-e3684f0cc5d6" xlink:href="amkr-20190930.xsd#amkr_ShorttermtermloanvariablerateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_ShorttermtermloanvariablerateMember_9b5e8f64-4ea7-49d3-9602-e3684f0cc5d6" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_TermLoanDueJune2022Member_15061f78-a96a-4dee-a37c-04cc077a2fff" xlink:href="amkr-20190930.xsd#amkr_TermLoanDueJune2022Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_TermLoanDueJune2022Member_15061f78-a96a-4dee-a37c-04cc077a2fff" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_TermLoanFixedRateat0.60DueJuly2022Member_415d531e-5bf1-4930-b02f-6055be25c3dc" xlink:href="amkr-20190930.xsd#amkr_TermLoanFixedRateat0.60DueJuly2022Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_TermLoanFixedRateat0.60DueJuly2022Member_415d531e-5bf1-4930-b02f-6055be25c3dc" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_TermLoanFixedRateat1.30DueJuly2023Member_86b1be32-2d3b-446c-8179-34b76edb144c" xlink:href="amkr-20190930.xsd#amkr_TermLoanFixedRateat1.30DueJuly2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_TermLoanFixedRateat1.30DueJuly2023Member_86b1be32-2d3b-446c-8179-34b76edb144c" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_TermLoanLIBORplus1.80dueDecember2019Member_6d68441a-0dbd-461f-906f-58ee9a839032" xlink:href="amkr-20190930.xsd#amkr_TermLoanLIBORplus1.80dueDecember2019Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_TermLoanLIBORplus1.80dueDecember2019Member_6d68441a-0dbd-461f-906f-58ee9a839032" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_TermLoanLIBORplus1.60dueMarch2022Member_df547b89-9771-40bc-8e9b-5a32db3c26d5" xlink:href="amkr-20190930.xsd#amkr_TermLoanLIBORplus1.60dueMarch2022Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_TermLoanLIBORplus1.60dueMarch2022Member_df547b89-9771-40bc-8e9b-5a32db3c26d5" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_TermLoanLIBORplus1.40dueMarch2022Member_506f9977-a016-4e2c-b55b-7d9182f67f2d" xlink:href="amkr-20190930.xsd#amkr_TermLoanLIBORplus1.40dueMarch2022Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_TermLoanLIBORplus1.40dueMarch2022Member_506f9977-a016-4e2c-b55b-7d9182f67f2d" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_SeniorSecuredRevolvingCreditFacilitydueJuly2023Member_d0383e55-3864-4365-8ed3-7e490b7ddc9f" xlink:href="amkr-20190930.xsd#amkr_SeniorSecuredRevolvingCreditFacilitydueJuly2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_SeniorSecuredRevolvingCreditFacilitydueJuly2023Member_d0383e55-3864-4365-8ed3-7e490b7ddc9f" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_RevolvingcreditfacilitydueNovember2020Member_38270c4f-4cd6-4232-a1cc-1c897e75df93" xlink:href="amkr-20190930.xsd#amkr_RevolvingcreditfacilitydueNovember2020Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_RevolvingcreditfacilitydueNovember2020Member_38270c4f-4cd6-4232-a1cc-1c897e75df93" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_RevolvingCreditFacilityDueOctober2020Member_3d3b3997-12d5-44cd-9a73-24639a3029f7" xlink:href="amkr-20190930.xsd#amkr_RevolvingCreditFacilityDueOctober2020Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_RevolvingCreditFacilityDueOctober2020Member_3d3b3997-12d5-44cd-9a73-24639a3029f7" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_AmkorAssemblyTestShanghaiCo.Ltd.TermLoanMember_d5dded73-720e-4645-ba72-8bc75150949a" xlink:href="amkr-20190930.xsd#amkr_AmkorAssemblyTestShanghaiCo.Ltd.TermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_28616ea8-0595-4655-8f73-dac5b3bca186" xlink:to="loc_amkr_AmkorAssemblyTestShanghaiCo.Ltd.TermLoanMember_d5dded73-720e-4645-ba72-8bc75150949a" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_048ba987-5857-4a0f-9aec-077f0faa2f1f" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_e7fdc3ac-b1cd-4c83-879f-9ddff65d9001" xlink:to="loc_us-gaap_CreditFacilityAxis_048ba987-5857-4a0f-9aec-077f0faa2f1f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_048ba987-5857-4a0f-9aec-077f0faa2f1f_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_048ba987-5857-4a0f-9aec-077f0faa2f1f" xlink:to="loc_us-gaap_CreditFacilityDomain_048ba987-5857-4a0f-9aec-077f0faa2f1f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_c546ceeb-25e5-42e7-8a10-f52d9d896c50" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_048ba987-5857-4a0f-9aec-077f0faa2f1f" xlink:to="loc_us-gaap_CreditFacilityDomain_c546ceeb-25e5-42e7-8a10-f52d9d896c50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_f30ec30a-b764-4915-894c-a7b89d6c8390" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_c546ceeb-25e5-42e7-8a10-f52d9d896c50" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_f30ec30a-b764-4915-894c-a7b89d6c8390" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_a7708914-f5d2-49b8-a558-6345d20264cb" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_e7fdc3ac-b1cd-4c83-879f-9ddff65d9001" xlink:to="loc_srt_StatementGeographicalAxis_a7708914-f5d2-49b8-a558-6345d20264cb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_a7708914-f5d2-49b8-a558-6345d20264cb_default" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_a7708914-f5d2-49b8-a558-6345d20264cb" xlink:to="loc_srt_SegmentGeographicalDomain_a7708914-f5d2-49b8-a558-6345d20264cb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_4ed7f3f6-aa57-470f-adc2-0e4f5da18332" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_a7708914-f5d2-49b8-a558-6345d20264cb" xlink:to="loc_srt_SegmentGeographicalDomain_4ed7f3f6-aa57-470f-adc2-0e4f5da18332" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_KR_b53062fe-962a-4fbc-927c-08d36d1da31d" xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_KR"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_4ed7f3f6-aa57-470f-adc2-0e4f5da18332" xlink:to="loc_country_KR_b53062fe-962a-4fbc-927c-08d36d1da31d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_JP_ca7f2604-9ec7-4752-882a-085e3e42572c" xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_JP"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_4ed7f3f6-aa57-470f-adc2-0e4f5da18332" xlink:to="loc_country_JP_ca7f2604-9ec7-4752-882a-085e3e42572c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_TW_ac75c649-f6bc-4894-96f0-07550fd7a841" xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_TW"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_4ed7f3f6-aa57-470f-adc2-0e4f5da18332" xlink:to="loc_country_TW_ac75c649-f6bc-4894-96f0-07550fd7a841" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CN_ce0f7212-dae9-4917-86e5-50aba9a8956c" xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_CN"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_4ed7f3f6-aa57-470f-adc2-0e4f5da18332" xlink:to="loc_country_CN_ce0f7212-dae9-4917-86e5-50aba9a8956c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_SG_e43e2761-9a4f-48f2-a356-377ce1bf2655" xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_SG"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_4ed7f3f6-aa57-470f-adc2-0e4f5da18332" xlink:to="loc_country_SG_e43e2761-9a4f-48f2-a356-377ce1bf2655" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_0356511d-8d0c-4833-accd-982e5583fd13" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_e7fdc3ac-b1cd-4c83-879f-9ddff65d9001" xlink:to="loc_us-gaap_VariableRateAxis_0356511d-8d0c-4833-accd-982e5583fd13" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_0356511d-8d0c-4833-accd-982e5583fd13_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_0356511d-8d0c-4833-accd-982e5583fd13" xlink:to="loc_us-gaap_VariableRateDomain_0356511d-8d0c-4833-accd-982e5583fd13_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_a0918a8a-f102-492d-b0af-36cd0355fb44" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_0356511d-8d0c-4833-accd-982e5583fd13" xlink:to="loc_us-gaap_VariableRateDomain_a0918a8a-f102-492d-b0af-36cd0355fb44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_TokyoInterbankOfferedRateTIBORMember_8869d9fe-7587-43fc-bc06-1d42821a2ad1" xlink:href="amkr-20190930.xsd#amkr_TokyoInterbankOfferedRateTIBORMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_a0918a8a-f102-492d-b0af-36cd0355fb44" xlink:to="loc_amkr_TokyoInterbankOfferedRateTIBORMember_8869d9fe-7587-43fc-bc06-1d42821a2ad1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_6e328ec9-e626-44d9-a1e9-cf259bc0e81e" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_a0918a8a-f102-492d-b0af-36cd0355fb44" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_6e328ec9-e626-44d9-a1e9-cf259bc0e81e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_FundFloatingRateMember_bc757b11-b96d-48a7-9172-900b67f317eb" xlink:href="amkr-20190930.xsd#amkr_FundFloatingRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_a0918a8a-f102-492d-b0af-36cd0355fb44" xlink:to="loc_amkr_FundFloatingRateMember_bc757b11-b96d-48a7-9172-900b67f317eb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_ApplicableBankRateMember_29000a4d-1281-48e9-b167-4853a7eb4450" xlink:href="amkr-20190930.xsd#amkr_ApplicableBankRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_a0918a8a-f102-492d-b0af-36cd0355fb44" xlink:to="loc_amkr_ApplicableBankRateMember_29000a4d-1281-48e9-b167-4853a7eb4450" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_50e28137-47c0-4198-92aa-c62f999d4448" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_e7fdc3ac-b1cd-4c83-879f-9ddff65d9001" xlink:to="loc_srt_RangeAxis_50e28137-47c0-4198-92aa-c62f999d4448" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_50e28137-47c0-4198-92aa-c62f999d4448_default" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_50e28137-47c0-4198-92aa-c62f999d4448" xlink:to="loc_srt_RangeMember_50e28137-47c0-4198-92aa-c62f999d4448_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_d2c16e9f-bd08-456a-83c6-1d5d9282779a" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_50e28137-47c0-4198-92aa-c62f999d4448" xlink:to="loc_srt_RangeMember_d2c16e9f-bd08-456a-83c6-1d5d9282779a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_10ce12fb-4974-4433-b56f-e899dc3d5a81" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_d2c16e9f-bd08-456a-83c6-1d5d9282779a" xlink:to="loc_srt_MinimumMember_10ce12fb-4974-4433-b56f-e899dc3d5a81" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_18408c73-3de0-4c5e-8f45-362e89b1b159" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_d2c16e9f-bd08-456a-83c6-1d5d9282779a" xlink:to="loc_srt_MaximumMember_18408c73-3de0-4c5e-8f45-362e89b1b159" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_WeightedAverageMember_60dd188e-ebee-46ef-8869-47d13fd96fa1" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_WeightedAverageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_d2c16e9f-bd08-456a-83c6-1d5d9282779a" xlink:to="loc_srt_WeightedAverageMember_60dd188e-ebee-46ef-8869-47d13fd96fa1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_36663420-6ef9-4af2-8514-63e2feec0073" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_e7fdc3ac-b1cd-4c83-879f-9ddff65d9001" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_36663420-6ef9-4af2-8514-63e2feec0073" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_36663420-6ef9-4af2-8514-63e2feec0073_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_36663420-6ef9-4af2-8514-63e2feec0073" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_36663420-6ef9-4af2-8514-63e2feec0073_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_5ac54991-7923-4314-b780-c0ec2936cd44" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_36663420-6ef9-4af2-8514-63e2feec0073" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_5ac54991-7923-4314-b780-c0ec2936cd44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_dc419c06-ad75-4286-843b-d6883847a45d" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_5ac54991-7923-4314-b780-c0ec2936cd44" xlink:to="loc_us-gaap_SubsequentEventMember_dc419c06-ad75-4286-843b-d6883847a45d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.amkor.com/role/PensionPlans" xlink:type="simple" xlink:href="amkr-20190930.xsd#PensionPlans"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/PensionPlans" xlink:type="extended" id="i9e2c828a9ee2453299264db67c2a88b3_34ed09c9-d01d-4765-89a3-e07afba69c34"/>
  <link:roleRef roleURI="http://www.amkor.com/role/PensionPlansTables" xlink:type="simple" xlink:href="amkr-20190930.xsd#PensionPlansTables"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/PensionPlansTables" xlink:type="extended" id="i5b9958661b8147f99582496b1fedb9ec_f0081d18-97b4-4999-bb7f-6fa3a7046ae9"/>
  <link:roleRef roleURI="http://www.amkor.com/role/PensionPlansComponentsofNetPeriodicPensionCostDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#PensionPlansComponentsofNetPeriodicPensionCostDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/PensionPlansComponentsofNetPeriodicPensionCostDetails" xlink:type="extended" id="i3a8aea95c98f4cbeb7449b83601c13e3_032e0b3b-04bc-43a6-a8dd-01d9c6adfad3"/>
  <link:roleRef roleURI="http://www.amkor.com/role/PensionPlansSummaryofDefinedContributionExpenseDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#PensionPlansSummaryofDefinedContributionExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/PensionPlansSummaryofDefinedContributionExpenseDetails" xlink:type="extended" id="idd44ab46ff7a402f89ddb2e07dd0150a_f6e7e0c3-ca0a-4360-8081-bf279a77635c"/>
  <link:roleRef roleURI="http://www.amkor.com/role/FairValueMeasurements" xlink:type="simple" xlink:href="amkr-20190930.xsd#FairValueMeasurements"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/FairValueMeasurements" xlink:type="extended" id="i4599dc2e64214081954bb25169d690e4_74330836-49ae-4b12-b84d-1680cec15040"/>
  <link:roleRef roleURI="http://www.amkor.com/role/FairValueMeasurementsTables" xlink:type="simple" xlink:href="amkr-20190930.xsd#FairValueMeasurementsTables"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/FairValueMeasurementsTables" xlink:type="extended" id="ief114e0706fe44bca1aa175bb7ab1382_a2375864-b9ed-467e-a381-bbf71d87717d"/>
  <link:roleRef roleURI="http://www.amkor.com/role/FairValueMeasurementsRecurringMeasurementsDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#FairValueMeasurementsRecurringMeasurementsDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/FairValueMeasurementsRecurringMeasurementsDetails" xlink:type="extended" id="id6cfcbc23fc645b48949602993016a1f_b2343f98-8dbc-42c1-b345-cdeb9545b634">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_25e78d92-5432-45af-b06f-abb6ad904221" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_6a32b0d3-8c97-4d28-a6b1-df8e9302cefa" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_25e78d92-5432-45af-b06f-abb6ad904221" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_6a32b0d3-8c97-4d28-a6b1-df8e9302cefa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_RestrictedCashFairValueDisclosure_9641ba1f-63de-4e8f-8da4-3777088d8aaa" xlink:href="amkr-20190930.xsd#amkr_RestrictedCashFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_25e78d92-5432-45af-b06f-abb6ad904221" xlink:to="loc_amkr_RestrictedCashFairValueDisclosure_9641ba1f-63de-4e8f-8da4-3777088d8aaa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_43acf0c4-d26c-44c5-8923-22df6b092e3b" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_25e78d92-5432-45af-b06f-abb6ad904221" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_43acf0c4-d26c-44c5-8923-22df6b092e3b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_a6787968-4014-4751-9869-c96492e3c6c8" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_43acf0c4-d26c-44c5-8923-22df6b092e3b" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_a6787968-4014-4751-9869-c96492e3c6c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_a6787968-4014-4751-9869-c96492e3c6c8_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_a6787968-4014-4751-9869-c96492e3c6c8" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_a6787968-4014-4751-9869-c96492e3c6c8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_0af86fd8-5dfb-4bbb-8591-28e974567520" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_a6787968-4014-4751-9869-c96492e3c6c8" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_0af86fd8-5dfb-4bbb-8591-28e974567520" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_d5adb560-29f9-4fee-9286-89de472b0909" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_0af86fd8-5dfb-4bbb-8591-28e974567520" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_d5adb560-29f9-4fee-9286-89de472b0909" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_fd8fd4ff-1e07-4de0-97ef-32725f6482bd" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_43acf0c4-d26c-44c5-8923-22df6b092e3b" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_fd8fd4ff-1e07-4de0-97ef-32725f6482bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_fd8fd4ff-1e07-4de0-97ef-32725f6482bd_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_fd8fd4ff-1e07-4de0-97ef-32725f6482bd" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_fd8fd4ff-1e07-4de0-97ef-32725f6482bd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1109a90c-803d-4548-a0d4-ffae418e669a" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_fd8fd4ff-1e07-4de0-97ef-32725f6482bd" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1109a90c-803d-4548-a0d4-ffae418e669a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_4fea90dc-84ca-41b4-be08-b4e46232817f" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1109a90c-803d-4548-a0d4-ffae418e669a" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_4fea90dc-84ca-41b4-be08-b4e46232817f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentTypeAxis_6ff0c042-2ad3-463e-9333-b850e27d1e58" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InvestmentTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_43acf0c4-d26c-44c5-8923-22df6b092e3b" xlink:to="loc_us-gaap_InvestmentTypeAxis_6ff0c042-2ad3-463e-9333-b850e27d1e58" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_6ff0c042-2ad3-463e-9333-b850e27d1e58_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_6ff0c042-2ad3-463e-9333-b850e27d1e58" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_6ff0c042-2ad3-463e-9333-b850e27d1e58_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_2a2cc740-d8bd-44da-9221-32896309d4ed" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_6ff0c042-2ad3-463e-9333-b850e27d1e58" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_2a2cc740-d8bd-44da-9221-32896309d4ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_752d6142-e9c2-42b3-984f-0c3a64fdfef4" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_2a2cc740-d8bd-44da-9221-32896309d4ed" xlink:to="loc_us-gaap_MoneyMarketFundsMember_752d6142-e9c2-42b3-984f-0c3a64fdfef4" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.amkor.com/role/FairValueMeasurementsInstrumentsNotRecordedonRecurringBasisDetails" xlink:type="simple" xlink:href="amkr-20190930.xsd#FairValueMeasurementsInstrumentsNotRecordedonRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/FairValueMeasurementsInstrumentsNotRecordedonRecurringBasisDetails" xlink:type="extended" id="iaef73341da9d4513ba2614eab5ccdf71_0e2c7809-406b-40ae-b5bb-b06ea18ca80f">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_a34928d9-d885-4414-9eba-ce14d35f71e9" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFairValue_be2230c3-a76b-46bb-b473-2b0604432648" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_a34928d9-d885-4414-9eba-ce14d35f71e9" xlink:to="loc_us-gaap_DebtInstrumentFairValue_be2230c3-a76b-46bb-b473-2b0604432648" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_e3420a71-def0-489e-82f7-5f771a9d223d" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByBalanceSheetGroupingTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_a34928d9-d885-4414-9eba-ce14d35f71e9" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_e3420a71-def0-489e-82f7-5f771a9d223d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_1773e166-ad0e-4721-a26b-61d4d388ebdb" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_e3420a71-def0-489e-82f7-5f771a9d223d" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_1773e166-ad0e-4721-a26b-61d4d388ebdb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_1773e166-ad0e-4721-a26b-61d4d388ebdb_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_1773e166-ad0e-4721-a26b-61d4d388ebdb" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_1773e166-ad0e-4721-a26b-61d4d388ebdb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_b42365fd-0476-4863-b8b5-7c9456503ca6" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_1773e166-ad0e-4721-a26b-61d4d388ebdb" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_b42365fd-0476-4863-b8b5-7c9456503ca6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_a30cfc50-ce47-42f0-b1b7-18e69b7abecc" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_b42365fd-0476-4863-b8b5-7c9456503ca6" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_a30cfc50-ce47-42f0-b1b7-18e69b7abecc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_43c74fd3-4fb9-4549-b896-182a40831f3b" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_b42365fd-0476-4863-b8b5-7c9456503ca6" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_43c74fd3-4fb9-4549-b896-182a40831f3b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_1ae1f977-609a-40cc-9193-c3a594b09cd3" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_b42365fd-0476-4863-b8b5-7c9456503ca6" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_1ae1f977-609a-40cc-9193-c3a594b09cd3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_7d1059b2-b649-4db7-bf7b-5c0243e775cb" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_e3420a71-def0-489e-82f7-5f771a9d223d" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_7d1059b2-b649-4db7-bf7b-5c0243e775cb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_7d1059b2-b649-4db7-bf7b-5c0243e775cb_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_7d1059b2-b649-4db7-bf7b-5c0243e775cb" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_7d1059b2-b649-4db7-bf7b-5c0243e775cb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_b1de9514-407c-4911-991e-e1759da7c9ca" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_7d1059b2-b649-4db7-bf7b-5c0243e775cb" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_b1de9514-407c-4911-991e-e1759da7c9ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_83e08646-decb-4ce6-aaf8-2fd5858e8f93" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_b1de9514-407c-4911-991e-e1759da7c9ca" xlink:to="loc_us-gaap_SeniorNotesMember_83e08646-decb-4ce6-aaf8-2fd5858e8f93" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_amkr_SubsidiaryTermLoansandRevolvingCreditFacilitiesMember_4ac7fc57-9582-42d6-841b-d29bf4a2a241" xlink:href="amkr-20190930.xsd#amkr_SubsidiaryTermLoansandRevolvingCreditFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_b1de9514-407c-4911-991e-e1759da7c9ca" xlink:to="loc_amkr_SubsidiaryTermLoansandRevolvingCreditFacilitiesMember_4ac7fc57-9582-42d6-841b-d29bf4a2a241" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_eb9e5789-da0b-439d-a800-587ca2d65031" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_e3420a71-def0-489e-82f7-5f771a9d223d" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_eb9e5789-da0b-439d-a800-587ca2d65031" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_eb9e5789-da0b-439d-a800-587ca2d65031_default" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_eb9e5789-da0b-439d-a800-587ca2d65031" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_eb9e5789-da0b-439d-a800-587ca2d65031_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0897b3a7-607f-4006-ac5c-0327c155c037" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_eb9e5789-da0b-439d-a800-587ca2d65031" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0897b3a7-607f-4006-ac5c-0327c155c037" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_73c3d30d-09ad-4e1c-a712-f8345f673e20" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0897b3a7-607f-4006-ac5c-0327c155c037" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_73c3d30d-09ad-4e1c-a712-f8345f673e20" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_2cc1aa49-332a-4f0a-ab48-06db6093e710" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0897b3a7-607f-4006-ac5c-0327c155c037" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_2cc1aa49-332a-4f0a-ab48-06db6093e710" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.amkor.com/role/CommitmentsandContingencies" xlink:type="simple" xlink:href="amkr-20190930.xsd#CommitmentsandContingencies"/>
  <link:definitionLink xlink:role="http://www.amkor.com/role/CommitmentsandContingencies" xlink:type="extended" id="i49adeca4233640ebad66c04403bb37d2_5a0c45cd-b22b-4ac8-ac26-a876bc6e8115"/>
</link:linkbase>
