<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:roleRef roleURI="http://www.amkor.com/role/AccruedExpenses" xlink:href="amkr-20190331.xsd#AccruedExpenses" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/AccruedExpensesDetails" xlink:href="amkr-20190331.xsd#AccruedExpensesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/AccruedExpensesTables" xlink:href="amkr-20190331.xsd#AccruedExpensesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/AccumulatedOtherComprehensiveIncomeLoss" xlink:href="amkr-20190331.xsd#AccumulatedOtherComprehensiveIncomeLoss" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/AccumulatedOtherComprehensiveIncomeLossChangesInAccumulatedOtherComprehensiveIncomeLossDetails" xlink:href="amkr-20190331.xsd#AccumulatedOtherComprehensiveIncomeLossChangesInAccumulatedOtherComprehensiveIncomeLossDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/AccumulatedOtherComprehensiveIncomeLossTables" xlink:href="amkr-20190331.xsd#AccumulatedOtherComprehensiveIncomeLossTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/CommitmentsAndContingencies" xlink:href="amkr-20190331.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:href="amkr-20190331.xsd#CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/ConsolidatedBalanceSheetsUnaudited" xlink:href="amkr-20190331.xsd#ConsolidatedBalanceSheetsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/ConsolidatedBalanceSheetsUnauditedParenthetical" xlink:href="amkr-20190331.xsd#ConsolidatedBalanceSheetsUnauditedParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/ConsolidatedStatementsOfComprehensiveIncomeUnaudited" xlink:href="amkr-20190331.xsd#ConsolidatedStatementsOfComprehensiveIncomeUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/ConsolidatedStatementsOfIncomeUnaudited" xlink:href="amkr-20190331.xsd#ConsolidatedStatementsOfIncomeUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/ConsolidatedStatementsOfStockholdersEquityUnaudited" xlink:href="amkr-20190331.xsd#ConsolidatedStatementsOfStockholdersEquityUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/Debt" xlink:href="amkr-20190331.xsd#Debt" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/DebtDetails" xlink:href="amkr-20190331.xsd#DebtDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/DebtTables" xlink:href="amkr-20190331.xsd#DebtTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/DocumentAndEntityInformationDocumentAndEntityInformation" xlink:href="amkr-20190331.xsd#DocumentAndEntityInformationDocumentAndEntityInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/EarningsPerShare" xlink:href="amkr-20190331.xsd#EarningsPerShare" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/EarningsPerShareComputationOfBasicAndDilutedEarningsPerShareDetails" xlink:href="amkr-20190331.xsd#EarningsPerShareComputationOfBasicAndDilutedEarningsPerShareDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/EarningsPerShareSummaryOfPotentialSharesOfCommonStockExcludedFromDilutedEpsDetails" xlink:href="amkr-20190331.xsd#EarningsPerShareSummaryOfPotentialSharesOfCommonStockExcludedFromDilutedEpsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/EarningsPerShareTables" xlink:href="amkr-20190331.xsd#EarningsPerShareTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/FactoringOfAccountsReceivable" xlink:href="amkr-20190331.xsd#FactoringOfAccountsReceivable" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/FactoringOfAccountsReceivableDetails" xlink:href="amkr-20190331.xsd#FactoringOfAccountsReceivableDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/FairValueMeasurements" xlink:href="amkr-20190331.xsd#FairValueMeasurements" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/FairValueMeasurementsFairValueOfFinancialInstrumentsNotRecordedAtFairValueOnRecurringBasisDetails" xlink:href="amkr-20190331.xsd#FairValueMeasurementsFairValueOfFinancialInstrumentsNotRecordedAtFairValueOnRecurringBasisDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/FairValueMeasurementsRecurringFairValueMeasurementsDetails" xlink:href="amkr-20190331.xsd#FairValueMeasurementsRecurringFairValueMeasurementsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/FairValueMeasurementsTables" xlink:href="amkr-20190331.xsd#FairValueMeasurementsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/IncomeTaxes" xlink:href="amkr-20190331.xsd#IncomeTaxes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/IncomeTaxesDetails" xlink:href="amkr-20190331.xsd#IncomeTaxesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/InterimFinancialStatements" xlink:href="amkr-20190331.xsd#InterimFinancialStatements" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/InterimFinancialStatementsDetails" xlink:href="amkr-20190331.xsd#InterimFinancialStatementsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/InterimFinancialStatementsPolicies" xlink:href="amkr-20190331.xsd#InterimFinancialStatementsPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/Leases" xlink:href="amkr-20190331.xsd#Leases" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/LeasesComponentsOfLeaseExpenseDetails" xlink:href="amkr-20190331.xsd#LeasesComponentsOfLeaseExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/LeasesFutureMinimumLeasePaymentsDetails" xlink:href="amkr-20190331.xsd#LeasesFutureMinimumLeasePaymentsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/LeasesTables" xlink:href="amkr-20190331.xsd#LeasesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/NetSalesByProductGroupAndEndMarket" xlink:href="amkr-20190331.xsd#NetSalesByProductGroupAndEndMarket" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/NetSalesByProductGroupAndEndMarketNetSalesByEndMarketDetails" xlink:href="amkr-20190331.xsd#NetSalesByProductGroupAndEndMarketNetSalesByEndMarketDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/NetSalesByProductGroupAndEndMarketNetSalesByProductGroupDetails" xlink:href="amkr-20190331.xsd#NetSalesByProductGroupAndEndMarketNetSalesByProductGroupDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/NetSalesByProductGroupAndEndMarketTables" xlink:href="amkr-20190331.xsd#NetSalesByProductGroupAndEndMarketTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/NewAccountingStandards" xlink:href="amkr-20190331.xsd#NewAccountingStandards" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/OtherIncomeAndExpense" xlink:href="amkr-20190331.xsd#OtherIncomeAndExpense" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/OtherIncomeAndExpenseDetails" xlink:href="amkr-20190331.xsd#OtherIncomeAndExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/OtherIncomeAndExpenseTables" xlink:href="amkr-20190331.xsd#OtherIncomeAndExpenseTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/PensionPlans" xlink:href="amkr-20190331.xsd#PensionPlans" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/PensionPlansComponentsOfNetPeriodicPensionCostDetails" xlink:href="amkr-20190331.xsd#PensionPlansComponentsOfNetPeriodicPensionCostDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/PensionPlansSummaryOfDefinedContributionExpenseDetails" xlink:href="amkr-20190331.xsd#PensionPlansSummaryOfDefinedContributionExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/PensionPlansTables" xlink:href="amkr-20190331.xsd#PensionPlansTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/PropertyPlantAndEquipment" xlink:href="amkr-20190331.xsd#PropertyPlantAndEquipment" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/PropertyPlantAndEquipmentSummaryOfDepreciationExpenseDetails" xlink:href="amkr-20190331.xsd#PropertyPlantAndEquipmentSummaryOfDepreciationExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/PropertyPlantAndEquipmentSummaryOfPropertyPlantAndEquipmentDetails" xlink:href="amkr-20190331.xsd#PropertyPlantAndEquipmentSummaryOfPropertyPlantAndEquipmentDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.amkor.com/role/PropertyPlantAndEquipmentTables" xlink:href="amkr-20190331.xsd#PropertyPlantAndEquipmentTables" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/AccruedExpenses" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/AccruedExpensesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/AccruedExpensesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/AccumulatedOtherComprehensiveIncomeLoss" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/AccumulatedOtherComprehensiveIncomeLossChangesInAccumulatedOtherComprehensiveIncomeLossDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_683FED0C2275C63F97DF27142D653D5F" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_A6162E28A37DE96C42E427142D647DE3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_683FED0C2275C63F97DF27142D653D5F" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_A6162E28A37DE96C42E427142D647DE3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_22EFD3C631C546B81A8527142D644D11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_A6162E28A37DE96C42E427142D647DE3" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_22EFD3C631C546B81A8527142D644D11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_70AFE8459E00CA49820727142D6485FE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_22EFD3C631C546B81A8527142D644D11" xlink:to="loc_us-gaap_EquityComponentDomain_70AFE8459E00CA49820727142D6485FE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_70AFE8459E00CA49820727142D6485FE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_22EFD3C631C546B81A8527142D644D11" xlink:to="loc_us-gaap_EquityComponentDomain_70AFE8459E00CA49820727142D6485FE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember_C6C3CFF904798BC3D53F27142D64671F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_70AFE8459E00CA49820727142D6485FE" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember_C6C3CFF904798BC3D53F27142D64671F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember" xlink:label="loc_us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember_DABC86E9DD2322770B0127142D65B894" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_70AFE8459E00CA49820727142D6485FE" xlink:to="loc_us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember_DABC86E9DD2322770B0127142D65B894" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AociIncludingPortionAttributableToNoncontrollingInterestMember" xlink:label="loc_us-gaap_AociIncludingPortionAttributableToNoncontrollingInterestMember_C9862AFC10CA4C949FBF27142D6571D3" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_70AFE8459E00CA49820727142D6485FE" xlink:to="loc_us-gaap_AociIncludingPortionAttributableToNoncontrollingInterestMember_C9862AFC10CA4C949FBF27142D6571D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_46357BB313176C20249D27142D65DAD4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_683FED0C2275C63F97DF27142D653D5F" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_46357BB313176C20249D27142D65DAD4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_3F98FA5652CC0F7CF36727142D66495B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_46357BB313176C20249D27142D65DAD4" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_3F98FA5652CC0F7CF36727142D66495B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_45A0024558CE4FD2F14927142D66BBBE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_46357BB313176C20249D27142D65DAD4" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_45A0024558CE4FD2F14927142D66BBBE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_71686C9E786FEDBB942327142D66DCE3" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_46357BB313176C20249D27142D65DAD4" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_71686C9E786FEDBB942327142D66DCE3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_BD7CFCEC092AEFED534527142D664801" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_46357BB313176C20249D27142D65DAD4" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_BD7CFCEC092AEFED534527142D664801" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.amkor.com/role/AccumulatedOtherComprehensiveIncomeLossTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/ConsolidatedBalanceSheetsUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/ConsolidatedBalanceSheetsUnauditedParenthetical" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/ConsolidatedStatementsOfComprehensiveIncomeUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/ConsolidatedStatementsOfIncomeUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/ConsolidatedStatementsOfStockholdersEquityUnaudited" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_6D88EC470B17B6287FAD79462901531E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_950FD4592DB77B6981C5794628FF12D0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_6D88EC470B17B6287FAD79462901531E" xlink:to="loc_us-gaap_StatementTable_950FD4592DB77B6981C5794628FF12D0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_3DAC4B82803683D0221F794629006F49" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_950FD4592DB77B6981C5794628FF12D0" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_3DAC4B82803683D0221F794629006F49" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_FE1DE1A9E38512876032794629003A82_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_3DAC4B82803683D0221F794629006F49" xlink:to="loc_us-gaap_EquityComponentDomain_FE1DE1A9E38512876032794629003A82_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_FE1DE1A9E38512876032794629003A82" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_3DAC4B82803683D0221F794629006F49" xlink:to="loc_us-gaap_EquityComponentDomain_FE1DE1A9E38512876032794629003A82" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ParentMember" xlink:label="loc_us-gaap_ParentMember_4D3144FA33BB8376D81E7946290007C3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_FE1DE1A9E38512876032794629003A82" xlink:to="loc_us-gaap_ParentMember_4D3144FA33BB8376D81E7946290007C3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_CA3A45EA5A8C787A8A7079462900227F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_4D3144FA33BB8376D81E7946290007C3" xlink:to="loc_us-gaap_CommonStockMember_CA3A45EA5A8C787A8A7079462900227F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_A1D7A85659717976FFAF7946290192CF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_4D3144FA33BB8376D81E7946290007C3" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_A1D7A85659717976FFAF7946290192CF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_DAD8D4B49DEEE06AF25C794629015700" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_4D3144FA33BB8376D81E7946290007C3" xlink:to="loc_us-gaap_RetainedEarningsMember_DAD8D4B49DEEE06AF25C794629015700" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_C7F145B9560CCF516D5A79462901C906" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_4D3144FA33BB8376D81E7946290007C3" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_C7F145B9560CCF516D5A79462901C906" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockMember" xlink:label="loc_us-gaap_TreasuryStockMember_19AD26BEEB3C2DE29D2979462901F333" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_4D3144FA33BB8376D81E7946290007C3" xlink:to="loc_us-gaap_TreasuryStockMember_19AD26BEEB3C2DE29D2979462901F333" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NoncontrollingInterestMember" xlink:label="loc_us-gaap_NoncontrollingInterestMember_F4BE276549165E740F6979462901B857" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_FE1DE1A9E38512876032794629003A82" xlink:to="loc_us-gaap_NoncontrollingInterestMember_F4BE276549165E740F6979462901B857" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_B245A715210E31599A8379462902C047" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_6D88EC470B17B6287FAD79462901531E" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_B245A715210E31599A8379462902C047" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="loc_us-gaap_CommonStockSharesIssued_B811C3A1C6C5F9B34FA4794629029F2E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_B245A715210E31599A8379462902C047" xlink:to="loc_us-gaap_CommonStockSharesIssued_B811C3A1C6C5F9B34FA4794629029F2E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockShares" xlink:label="loc_us-gaap_TreasuryStockShares_55E62FE78E0302C58B00794629021C2E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_B245A715210E31599A8379462902C047" xlink:to="loc_us-gaap_TreasuryStockShares_55E62FE78E0302C58B00794629021C2E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_D149C221DA1E79D8DDE679462902AE98" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_B245A715210E31599A8379462902C047" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_D149C221DA1E79D8DDE679462902AE98" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProfitLoss" xlink:label="loc_us-gaap_ProfitLoss_6A63B0746EBEFE7B8C8779462903E9D9" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_B245A715210E31599A8379462902C047" xlink:to="loc_us-gaap_ProfitLoss_6A63B0746EBEFE7B8C8779462903E9D9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_58C7EF3BA1A5CE314C2C79462903328A" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_B245A715210E31599A8379462902C047" xlink:to="loc_us-gaap_NetIncomeLoss_58C7EF3BA1A5CE314C2C79462903328A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_B228A8EDF04F77DB3C8579462903C9AB" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_B245A715210E31599A8379462902C047" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_B228A8EDF04F77DB3C8579462903C9AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_88CF11FE56174DA21D4579462903BF29" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_B245A715210E31599A8379462902C047" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_88CF11FE56174DA21D4579462903BF29" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_D724C0B4769E3D318723794629034DBC" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_B245A715210E31599A8379462902C047" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_D724C0B4769E3D318723794629034DBC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_AAB0710EB23CFF66A2B0794629032ED2" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_B245A715210E31599A8379462902C047" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_AAB0710EB23CFF66A2B0794629032ED2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_2A961BC3B49174CF160D79462903C787" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_B245A715210E31599A8379462902C047" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_2A961BC3B49174CF160D79462903C787" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_0B9249430D416545A2AE794629047F8B" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_B245A715210E31599A8379462902C047" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_0B9249430D416545A2AE794629047F8B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_1882040780C4E8E99F9879462904681E" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_B245A715210E31599A8379462902C047" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_1882040780C4E8E99F9879462904681E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_E8D45296E32F5110525679462904CCE2" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_B245A715210E31599A8379462902C047" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_E8D45296E32F5110525679462904CCE2" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.amkor.com/role/Debt" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/DebtDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_15E1ECD25DA18000EF4D7946281A9F17" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_us-gaap_DebtInstrumentTable_15E1ECD25DA18000EF4D7946281A9F17" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_F31A128C5BDB54D7E8AB7946281AF643" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_15E1ECD25DA18000EF4D7946281A9F17" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_F31A128C5BDB54D7E8AB7946281AF643" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_7A474C69669D9B285EF47946281B151A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_F31A128C5BDB54D7E8AB7946281AF643" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_7A474C69669D9B285EF47946281B151A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_7A474C69669D9B285EF47946281B151A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_F31A128C5BDB54D7E8AB7946281AF643" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_7A474C69669D9B285EF47946281B151A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditMember" xlink:label="loc_us-gaap_LineOfCreditMember_2227344B73F0665781557946281B9450" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_7A474C69669D9B285EF47946281B151A" xlink:to="loc_us-gaap_LineOfCreditMember_2227344B73F0665781557946281B9450" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SeniorNotesMember" xlink:label="loc_us-gaap_SeniorNotesMember_EB606BAADE8BE89455BF7946281B703D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_7A474C69669D9B285EF47946281B151A" xlink:to="loc_us-gaap_SeniorNotesMember_EB606BAADE8BE89455BF7946281B703D" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_SubsidiaryTermLoansMember" xlink:label="loc_amkr_SubsidiaryTermLoansMember_0D4A98D9DA53DD1F1B5A7946281CA34F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_7A474C69669D9B285EF47946281B151A" xlink:to="loc_amkr_SubsidiaryTermLoansMember_0D4A98D9DA53DD1F1B5A7946281CA34F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MediumTermNotesMember" xlink:label="loc_us-gaap_MediumTermNotesMember_22BA8E536C0C5E624FDB7946281CC9C3" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_7A474C69669D9B285EF47946281B151A" xlink:to="loc_us-gaap_MediumTermNotesMember_22BA8E536C0C5E624FDB7946281CC9C3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_8D9322AC2942DFA270CD79462821DA8F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_15E1ECD25DA18000EF4D7946281A9F17" xlink:to="loc_us-gaap_DebtInstrumentAxis_8D9322AC2942DFA270CD79462821DA8F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_8D9322AC2942DFA270CD79462821DA8F" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_8D9322AC2942DFA270CD79462821DA8F" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_SeniorNotesDueOctober2022Member" xlink:label="loc_amkr_SeniorNotesDueOctober2022Member_10750A3DF68245232C577946282183B7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:to="loc_amkr_SeniorNotesDueOctober2022Member_10750A3DF68245232C577946282183B7" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_SeniorNotesDueSeptember2027Member" xlink:label="loc_amkr_SeniorNotesDueSeptember2027Member_B19973C4A9A22153D22979462822A08A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:to="loc_amkr_SeniorNotesDueSeptember2027Member_B19973C4A9A22153D22979462822A08A" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_RevolvingCreditFacilitydueOctober2019Member" xlink:label="loc_amkr_RevolvingCreditFacilitydueOctober2019Member_73063EE2B4A6E515DAA57946282299ED" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:to="loc_amkr_RevolvingCreditFacilitydueOctober2019Member_73063EE2B4A6E515DAA57946282299ED" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_FixedRateTermLoanDueMay2020Member" xlink:label="loc_amkr_FixedRateTermLoanDueMay2020Member_B5C0300723DE45C57647794628228DCE" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:to="loc_amkr_FixedRateTermLoanDueMay2020Member_B5C0300723DE45C57647794628228DCE" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_TermLoanDueJune2020Member" xlink:label="loc_amkr_TermLoanDueJune2020Member_FDBB0907D522F2CE2CFA794628225BE5" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:to="loc_amkr_TermLoanDueJune2020Member_FDBB0907D522F2CE2CFA794628225BE5" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_TermLoanDueDecember2023Member" xlink:label="loc_amkr_TermLoanDueDecember2023Member_A35BBE5159DF4BB94E6F7946282250A6" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:to="loc_amkr_TermLoanDueDecember2023Member_A35BBE5159DF4BB94E6F7946282250A6" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_TermLoanDueDecember2028Member" xlink:label="loc_amkr_TermLoanDueDecember2028Member_3FAEF056043B0F849AE6794628237830" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:to="loc_amkr_TermLoanDueDecember2028Member_3FAEF056043B0F849AE6794628237830" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_ShorttermtermloanvariablerateMember" xlink:label="loc_amkr_ShorttermtermloanvariablerateMember_D4B1B59241E22294D886794628239D3D" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:to="loc_amkr_ShorttermtermloanvariablerateMember_D4B1B59241E22294D886794628239D3D" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_TermLoanDueJune2022Member" xlink:label="loc_amkr_TermLoanDueJune2022Member_1FBF94594065AE36EB6179462823212E" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:to="loc_amkr_TermLoanDueJune2022Member_1FBF94594065AE36EB6179462823212E" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_TermLoanFixedRateat0.60DueJuly2022Member" xlink:label="loc_amkr_TermLoanFixedRateat0.60DueJuly2022Member_40DE9F49A8D9029E585579462823FEED" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:to="loc_amkr_TermLoanFixedRateat0.60DueJuly2022Member_40DE9F49A8D9029E585579462823FEED" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_TermLoanFixedRateat1.30DueJuly2023Member" xlink:label="loc_amkr_TermLoanFixedRateat1.30DueJuly2023Member_3338DD582DB5FE24B28A79462823A9F8" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:to="loc_amkr_TermLoanFixedRateat1.30DueJuly2023Member_3338DD582DB5FE24B28A79462823A9F8" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_TermLoanLIBORplus1.80dueDecember2019Member" xlink:label="loc_amkr_TermLoanLIBORplus1.80dueDecember2019Member_23C7CD391CA9BD5FFCA3794628237A79" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:to="loc_amkr_TermLoanLIBORplus1.80dueDecember2019Member_23C7CD391CA9BD5FFCA3794628237A79" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_TermLoanLIBORplus1.60dueMarch2022Member" xlink:label="loc_amkr_TermLoanLIBORplus1.60dueMarch2022Member_7D047629F1C4751632E779462824E029" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:to="loc_amkr_TermLoanLIBORplus1.60dueMarch2022Member_7D047629F1C4751632E779462824E029" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_SeniorSecuredRevolvingCreditFacilitydueJuly2023Member" xlink:label="loc_amkr_SeniorSecuredRevolvingCreditFacilitydueJuly2023Member_14C5EA8D970DD1B20A2F794628246E28" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:to="loc_amkr_SeniorSecuredRevolvingCreditFacilitydueJuly2023Member_14C5EA8D970DD1B20A2F794628246E28" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_RevolvingcreditfacilitydueNovember2020Member" xlink:label="loc_amkr_RevolvingcreditfacilitydueNovember2020Member_01265E16F1D5C6596242794628244348" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:to="loc_amkr_RevolvingcreditfacilitydueNovember2020Member_01265E16F1D5C6596242794628244348" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_AmkorAssemblyTestShanghaiCo.Ltd.TermLoanMember" xlink:label="loc_amkr_AmkorAssemblyTestShanghaiCo.Ltd.TermLoanMember_658684A41512FE1FF1F1794628244E5F" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_BA9DE56FBEE1F6E32E9179462821177F" xlink:to="loc_amkr_AmkorAssemblyTestShanghaiCo.Ltd.TermLoanMember_658684A41512FE1FF1F1794628244E5F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_9241448B6146A4AE4F74794628240512" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_15E1ECD25DA18000EF4D7946281A9F17" xlink:to="loc_us-gaap_CreditFacilityAxis_9241448B6146A4AE4F74794628240512" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_F29515D66BE700D1A176794628243660_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_9241448B6146A4AE4F74794628240512" xlink:to="loc_us-gaap_CreditFacilityDomain_F29515D66BE700D1A176794628243660_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_F29515D66BE700D1A176794628243660" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_9241448B6146A4AE4F74794628240512" xlink:to="loc_us-gaap_CreditFacilityDomain_F29515D66BE700D1A176794628243660" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_94B4556A5A51C19B4A1A79462825A15D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_F29515D66BE700D1A176794628243660" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_94B4556A5A51C19B4A1A79462825A15D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_StatementGeographicalAxis" xlink:label="loc_srt_StatementGeographicalAxis_6AC48ADF85152A2A1FE5794628255F3C" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_15E1ECD25DA18000EF4D7946281A9F17" xlink:to="loc_srt_StatementGeographicalAxis_6AC48ADF85152A2A1FE5794628255F3C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_089FFAFED2768DC43CA27946282501C0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_6AC48ADF85152A2A1FE5794628255F3C" xlink:to="loc_srt_SegmentGeographicalDomain_089FFAFED2768DC43CA27946282501C0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_089FFAFED2768DC43CA27946282501C0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_6AC48ADF85152A2A1FE5794628255F3C" xlink:to="loc_srt_SegmentGeographicalDomain_089FFAFED2768DC43CA27946282501C0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_KR" xlink:label="loc_country_KR_E54558868B54BCB1222279462825313C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_089FFAFED2768DC43CA27946282501C0" xlink:to="loc_country_KR_E54558868B54BCB1222279462825313C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_JP" xlink:label="loc_country_JP_E03C6A8AB8769E1A392779462826489E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_089FFAFED2768DC43CA27946282501C0" xlink:to="loc_country_JP_E03C6A8AB8769E1A392779462826489E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_TW" xlink:label="loc_country_TW_AA70EFA0B9605D9253287946282613D5" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_089FFAFED2768DC43CA27946282501C0" xlink:to="loc_country_TW_AA70EFA0B9605D9253287946282613D5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_CN" xlink:label="loc_country_CN_B311508312B8B990738279462826C6AC" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_089FFAFED2768DC43CA27946282501C0" xlink:to="loc_country_CN_B311508312B8B990738279462826C6AC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_AF49E6F2CD8A7C0FE5D279462826D32F" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_15E1ECD25DA18000EF4D7946281A9F17" xlink:to="loc_us-gaap_VariableRateAxis_AF49E6F2CD8A7C0FE5D279462826D32F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_FE44ACDD58D671B062107946282643C5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_AF49E6F2CD8A7C0FE5D279462826D32F" xlink:to="loc_us-gaap_VariableRateDomain_FE44ACDD58D671B062107946282643C5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_FE44ACDD58D671B062107946282643C5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_AF49E6F2CD8A7C0FE5D279462826D32F" xlink:to="loc_us-gaap_VariableRateDomain_FE44ACDD58D671B062107946282643C5" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_TokyoInterbankOfferedRateTIBORMember" xlink:label="loc_amkr_TokyoInterbankOfferedRateTIBORMember_474A0B9D34CCFCEAAF6679462827DAFB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_FE44ACDD58D671B062107946282643C5" xlink:to="loc_amkr_TokyoInterbankOfferedRateTIBORMember_474A0B9D34CCFCEAAF6679462827DAFB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_11B9DBBA47663FC38C5C79462827873E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_FE44ACDD58D671B062107946282643C5" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_11B9DBBA47663FC38C5C79462827873E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_AE91BB23BE654A5C853179462827E0FF" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_15E1ECD25DA18000EF4D7946281A9F17" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_AE91BB23BE654A5C853179462827E0FF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_AC79AA374B1D2BC2B91979462827738B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_AE91BB23BE654A5C853179462827E0FF" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_AC79AA374B1D2BC2B91979462827738B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_AC79AA374B1D2BC2B91979462827738B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_AE91BB23BE654A5C853179462827E0FF" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_AC79AA374B1D2BC2B91979462827738B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_AA4F1C17962BB332DB5B7946282824B0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_AC79AA374B1D2BC2B91979462827738B" xlink:to="loc_us-gaap_SubsequentEventMember_AA4F1C17962BB332DB5B7946282824B0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_4868A52194D8D2D3954A794628282C63" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_15E1ECD25DA18000EF4D7946281A9F17" xlink:to="loc_us-gaap_StatementScenarioAxis_4868A52194D8D2D3954A794628282C63" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_2B91F2C334B426BA3481794628285185_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_4868A52194D8D2D3954A794628282C63" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_2B91F2C334B426BA3481794628285185_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_2B91F2C334B426BA3481794628285185" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_4868A52194D8D2D3954A794628282C63" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_2B91F2C334B426BA3481794628285185" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioForecastMember" xlink:label="loc_us-gaap_ScenarioForecastMember_A6A01CE8C0B490B4E4B3794628289E1A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_2B91F2C334B426BA3481794628285185" xlink:to="loc_us-gaap_ScenarioForecastMember_A6A01CE8C0B490B4E4B3794628289E1A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_319004A26AEDD8E1C0F979462828A0AB" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_15E1ECD25DA18000EF4D7946281A9F17" xlink:to="loc_srt_RangeAxis_319004A26AEDD8E1C0F979462828A0AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_A0E4338C39E1E936EEA0794628291878_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_319004A26AEDD8E1C0F979462828A0AB" xlink:to="loc_srt_RangeMember_A0E4338C39E1E936EEA0794628291878_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_A0E4338C39E1E936EEA0794628291878" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_319004A26AEDD8E1C0F979462828A0AB" xlink:to="loc_srt_RangeMember_A0E4338C39E1E936EEA0794628291878" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_546CAB2AE4F82DD1F19F79462829E88F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_A0E4338C39E1E936EEA0794628291878" xlink:to="loc_srt_MinimumMember_546CAB2AE4F82DD1F19F79462829E88F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_EFD9883B58272E5F7FF279462829A0C1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_A0E4338C39E1E936EEA0794628291878" xlink:to="loc_srt_MaximumMember_EFD9883B58272E5F7FF279462829A0C1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_WeightedAverageMember" xlink:label="loc_srt_WeightedAverageMember_866FE9F273C1673D5867794628294AD5" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_A0E4338C39E1E936EEA0794628291878" xlink:to="loc_srt_WeightedAverageMember_866FE9F273C1673D5867794628294AD5" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_LongtermDebtIncludingRelatedPartyGross" xlink:label="loc_amkr_LongtermDebtIncludingRelatedPartyGross_3F65554D9099557AB163794CC54E335B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_amkr_LongtermDebtIncludingRelatedPartyGross_3F65554D9099557AB163794CC54E335B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_1923F2462C58FA0196AE7946282A5419" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_1923F2462C58FA0196AE7946282A5419" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_DebtIncludingDuetoRelatedPartyCurrent" xlink:label="loc_amkr_DebtIncludingDuetoRelatedPartyCurrent_3B42FF356EC4CF14A2EE7946282AEACD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_amkr_DebtIncludingDuetoRelatedPartyCurrent_3B42FF356EC4CF14A2EE7946282AEACD" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_NonCurrentLongTermDebtIncludingRelatedParty" xlink:label="loc_amkr_NonCurrentLongTermDebtIncludingRelatedParty_BB149FEB420EE496DD9A7946282F4D15" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_amkr_NonCurrentLongTermDebtIncludingRelatedParty_BB149FEB420EE496DD9A7946282F4D15" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_DD9060A1D82A36B1303379462830E5EA" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_DD9060A1D82A36B1303379462830E5EA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_2B44CDD810ED6E1FF7AB79462830B987" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_2B44CDD810ED6E1FF7AB79462830B987" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_BB22B1652C269F12521C794628304B8C" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_BB22B1652C269F12521C794628304B8C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_10BF5E6A235360B428F9794628315EDB" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_10BF5E6A235360B428F9794628315EDB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_22A32A3A3EDF93980A6479462830BC24" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_22A32A3A3EDF93980A6479462830BC24" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ExtinguishmentOfDebtGainLossNetOfTax" xlink:label="loc_us-gaap_ExtinguishmentOfDebtGainLossNetOfTax_0696CA79228301515C5A794628308A42" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_us-gaap_ExtinguishmentOfDebtGainLossNetOfTax_0696CA79228301515C5A794628308A42" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_DebtInstrumentIssuancePercentageofPar" xlink:label="loc_amkr_DebtInstrumentIssuancePercentageofPar_07DA962CE3BAF5C499FA79462831C016" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_amkr_DebtInstrumentIssuancePercentageofPar_07DA962CE3BAF5C499FA79462831C016" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_8A31923D10AD849181F3794628316623" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_8A31923D10AD849181F3794628316623" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredFinanceCostsGross" xlink:label="loc_us-gaap_DeferredFinanceCostsGross_AA5909C60007D140A86779462831AB0F" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_us-gaap_DeferredFinanceCostsGross_AA5909C60007D140A86779462831AB0F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_A34AD57B744B2A6161DD7946283188C7" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_A34AD57B744B2A6161DD7946283188C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_0EC1D0D6D957B79589587946283129B4" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_0EC1D0D6D957B79589587946283129B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_94D1D497C04B57A4228079462832FC2C" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_94D1D497C04B57A4228079462832FC2C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentPeriodicPaymentPrincipal" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_362E3FBC15B2BE719DCE794628326216" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_362E3FBC15B2BE719DCE794628326216" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentTerm" xlink:label="loc_us-gaap_DebtInstrumentTerm_1104E788F90D58DC79027946283294FE" xlink:type="locator" />
    <link:definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_us-gaap_DebtInstrumentTerm_1104E788F90D58DC79027946283294FE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_D3B7A9A0415C20D4AEF4794628325999" xlink:type="locator" />
    <link:definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6EB2541C7D4F9B2A7AF27946282A1640" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_D3B7A9A0415C20D4AEF4794628325999" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.amkor.com/role/DebtTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/DocumentAndEntityInformationDocumentAndEntityInformation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/EarningsPerShare" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/EarningsPerShareComputationOfBasicAndDilutedEarningsPerShareDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/EarningsPerShareSummaryOfPotentialSharesOfCommonStockExcludedFromDilutedEpsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_BB92CA82A7013B03A98D270704A80157" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1A8736A5D3E6CBE532A4270704A5610D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_BB92CA82A7013B03A98D270704A80157" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1A8736A5D3E6CBE532A4270704A5610D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_B64F061C6EAEEF137470270704A5E3AF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1A8736A5D3E6CBE532A4270704A5610D" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_B64F061C6EAEEF137470270704A5E3AF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_27CDC71C0D0E9E5EA4AB270704A61164_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_B64F061C6EAEEF137470270704A5E3AF" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_27CDC71C0D0E9E5EA4AB270704A61164_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_27CDC71C0D0E9E5EA4AB270704A61164" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_B64F061C6EAEEF137470270704A5E3AF" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_27CDC71C0D0E9E5EA4AB270704A61164" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_StockOptionsAndRestrictedSharesMember" xlink:label="loc_amkr_StockOptionsAndRestrictedSharesMember_0C9305ABFF10506893EE270704A759BA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_27CDC71C0D0E9E5EA4AB270704A61164" xlink:to="loc_amkr_StockOptionsAndRestrictedSharesMember_0C9305ABFF10506893EE270704A759BA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_8E43DA8492BF062BA734270704A8585A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_BB92CA82A7013B03A98D270704A80157" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_8E43DA8492BF062BA734270704A8585A" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.amkor.com/role/EarningsPerShareTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/FactoringOfAccountsReceivable" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/FactoringOfAccountsReceivableDetails" xlink:type="extended">
    <link:loc xlink:href="amkr-20190331.xsd#amkr_FactoringofAccountsReceivableLineItems" xlink:label="loc_amkr_FactoringofAccountsReceivableLineItems_82310857A6B7CB316AF52707056B7364" xlink:type="locator" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_FactoringofAccountsReceivableTable" xlink:label="loc_amkr_FactoringofAccountsReceivableTable_6515EF2A987677913122270705649FD3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_amkr_FactoringofAccountsReceivableLineItems_82310857A6B7CB316AF52707056B7364" xlink:to="loc_amkr_FactoringofAccountsReceivableTable_6515EF2A987677913122270705649FD3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_FactoringofAccountsReceivableAxis" xlink:label="loc_amkr_FactoringofAccountsReceivableAxis_1CE4676C3A5FC73BCE8927070565FF80" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_amkr_FactoringofAccountsReceivableTable_6515EF2A987677913122270705649FD3" xlink:to="loc_amkr_FactoringofAccountsReceivableAxis_1CE4676C3A5FC73BCE8927070565FF80" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_FactoringofAccountsReceivableDomain" xlink:label="loc_amkr_FactoringofAccountsReceivableDomain_AC430D881C0FFD94D0872707056510C3_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_amkr_FactoringofAccountsReceivableAxis_1CE4676C3A5FC73BCE8927070565FF80" xlink:to="loc_amkr_FactoringofAccountsReceivableDomain_AC430D881C0FFD94D0872707056510C3_default" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_FactoringofAccountsReceivableDomain" xlink:label="loc_amkr_FactoringofAccountsReceivableDomain_AC430D881C0FFD94D0872707056510C3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_amkr_FactoringofAccountsReceivableAxis_1CE4676C3A5FC73BCE8927070565FF80" xlink:to="loc_amkr_FactoringofAccountsReceivableDomain_AC430D881C0FFD94D0872707056510C3" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_TotalFactoredMember" xlink:label="loc_amkr_TotalFactoredMember_44722B2F003DEEE3D75827070565CEBC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_amkr_FactoringofAccountsReceivableDomain_AC430D881C0FFD94D0872707056510C3" xlink:to="loc_amkr_TotalFactoredMember_44722B2F003DEEE3D75827070565CEBC" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_FactoringFeesMember" xlink:label="loc_amkr_FactoringFeesMember_85D3600696B5D63AA2EE270705653C45" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_amkr_FactoringofAccountsReceivableDomain_AC430D881C0FFD94D0872707056510C3" xlink:to="loc_amkr_FactoringFeesMember_85D3600696B5D63AA2EE270705653C45" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_AccountsReceivableSoldwithoutRecourse" xlink:label="loc_amkr_AccountsReceivableSoldwithoutRecourse_7948A1A226B3D8D59E8E2707056B8F78" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_amkr_FactoringofAccountsReceivableLineItems_82310857A6B7CB316AF52707056B7364" xlink:to="loc_amkr_AccountsReceivableSoldwithoutRecourse_7948A1A226B3D8D59E8E2707056B8F78" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.amkor.com/role/FairValueMeasurements" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/FairValueMeasurementsFairValueOfFinancialInstrumentsNotRecordedAtFairValueOnRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_D2EAA40D0A89F115D9C8270704782717" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByBalanceSheetGroupingTable" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_E9B8C57A15EFA1EC85962707046BEFAB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_D2EAA40D0A89F115D9C8270704782717" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_E9B8C57A15EFA1EC85962707046BEFAB" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByMeasurementBasisAxis" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_69D6F2A4731979E1AF792707046C023C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_E9B8C57A15EFA1EC85962707046BEFAB" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_69D6F2A4731979E1AF792707046C023C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_88AA6AA05831F99F669B2707046CFB28_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_69D6F2A4731979E1AF792707046C023C" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_88AA6AA05831F99F669B2707046CFB28_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueDisclosureItemAmountsDomain" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_E4C6AE1B8CF4F8FD16E22707046C8356" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_69D6F2A4731979E1AF792707046C023C" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_E4C6AE1B8CF4F8FD16E22707046C8356" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_88AA6AA05831F99F669B2707046CFB28" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_E4C6AE1B8CF4F8FD16E22707046C8356" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_88AA6AA05831F99F669B2707046CFB28" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_AFECEA47BB2CD40811472707046DFD58" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_E4C6AE1B8CF4F8FD16E22707046C8356" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_AFECEA47BB2CD40811472707046DFD58" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_E67B99A00BFB21FD0CD92707046DA989" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_E4C6AE1B8CF4F8FD16E22707046C8356" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_E67B99A00BFB21FD0CD92707046DA989" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_A904573A431543A6F79B2707046D7276" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_E9B8C57A15EFA1EC85962707046BEFAB" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_A904573A431543A6F79B2707046D7276" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_8CA0D9ED6F82EE738C0E2707046EF658_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_A904573A431543A6F79B2707046D7276" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_8CA0D9ED6F82EE738C0E2707046EF658_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_8CA0D9ED6F82EE738C0E2707046EF658" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_A904573A431543A6F79B2707046D7276" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_8CA0D9ED6F82EE738C0E2707046EF658" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SeniorNotesMember" xlink:label="loc_us-gaap_SeniorNotesMember_4A861B0FF4AEE33960D52707046FBA61" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_8CA0D9ED6F82EE738C0E2707046EF658" xlink:to="loc_us-gaap_SeniorNotesMember_4A861B0FF4AEE33960D52707046FBA61" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_SubsidiaryTermLoansandRevolvingCreditFacilitiesMember" xlink:label="loc_amkr_SubsidiaryTermLoansandRevolvingCreditFacilitiesMember_E189CAE67E497A2FB28E2707046F131E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_8CA0D9ED6F82EE738C0E2707046EF658" xlink:to="loc_amkr_SubsidiaryTermLoansandRevolvingCreditFacilitiesMember_E189CAE67E497A2FB28E2707046F131E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9667C991BA7A8D8E3C0D2707046FCE15" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_E9B8C57A15EFA1EC85962707046BEFAB" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9667C991BA7A8D8E3C0D2707046FCE15" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_BD19210CDB82D96FD554270704704199_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9667C991BA7A8D8E3C0D2707046FCE15" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_BD19210CDB82D96FD554270704704199_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_BD19210CDB82D96FD554270704704199" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9667C991BA7A8D8E3C0D2707046FCE15" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_BD19210CDB82D96FD554270704704199" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_938839B30DAD19AE1D5927070470C183" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_BD19210CDB82D96FD554270704704199" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_938839B30DAD19AE1D5927070470C183" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_9385FE72C400C5DEFF06270704784E87" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_BD19210CDB82D96FD554270704704199" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_9385FE72C400C5DEFF06270704784E87" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentFairValue" xlink:label="loc_us-gaap_DebtInstrumentFairValue_8CE57C2F9FDCD278326A27070478ABB1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_D2EAA40D0A89F115D9C8270704782717" xlink:to="loc_us-gaap_DebtInstrumentFairValue_8CE57C2F9FDCD278326A27070478ABB1" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.amkor.com/role/FairValueMeasurementsRecurringFairValueMeasurementsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0704DB2AE712EF4FC14F27070601A4EC" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_0788007BEFBC2314F5B3270705FE6D8F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0704DB2AE712EF4FC14F27070601A4EC" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_0788007BEFBC2314F5B3270705FE6D8F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_A9D52E288B54DA51FA37270705FF9F33" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_0788007BEFBC2314F5B3270705FE6D8F" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_A9D52E288B54DA51FA37270705FF9F33" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_2F6B3F0FE53A9679DD88270705FF75AB_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_A9D52E288B54DA51FA37270705FF9F33" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_2F6B3F0FE53A9679DD88270705FF75AB_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_2F6B3F0FE53A9679DD88270705FF75AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_A9D52E288B54DA51FA37270705FF9F33" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_2F6B3F0FE53A9679DD88270705FF75AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_A62E316EB47A3D6F78CF270705FF0669" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_2F6B3F0FE53A9679DD88270705FF75AB" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_A62E316EB47A3D6F78CF270705FF0669" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_BBF7C4323A298E960B2C270706009CB5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_0788007BEFBC2314F5B3270705FE6D8F" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_BBF7C4323A298E960B2C270706009CB5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7DAE0747470C8A118D382707060014B7_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_BBF7C4323A298E960B2C270706009CB5" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7DAE0747470C8A118D382707060014B7_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7DAE0747470C8A118D382707060014B7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_BBF7C4323A298E960B2C270706009CB5" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7DAE0747470C8A118D382707060014B7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_52B54CC0088B3B26373A27070600ED77" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7DAE0747470C8A118D382707060014B7" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_52B54CC0088B3B26373A27070600ED77" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_DEDC52D4997C8C1D8E4C27070601EF9D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0704DB2AE712EF4FC14F27070601A4EC" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_DEDC52D4997C8C1D8E4C27070601EF9D" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_RestrictedCashFairValueDisclosure" xlink:label="loc_amkr_RestrictedCashFairValueDisclosure_0127693883B392FB424727070601C867" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0704DB2AE712EF4FC14F27070601A4EC" xlink:to="loc_amkr_RestrictedCashFairValueDisclosure_0127693883B392FB424727070601C867" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.amkor.com/role/FairValueMeasurementsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/IncomeTaxes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/IncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxContingencyLineItems" xlink:label="loc_us-gaap_IncomeTaxContingencyLineItems_AD2C85762834339E977F770A1F571B0C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxContingencyTable" xlink:label="loc_us-gaap_IncomeTaxContingencyTable_90B7537B00D043748752770A1F3AD9CA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_AD2C85762834339E977F770A1F571B0C" xlink:to="loc_us-gaap_IncomeTaxContingencyTable_90B7537B00D043748752770A1F3AD9CA" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_2A6EF9DFC104A0635E17770A1F47F252" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_90B7537B00D043748752770A1F3AD9CA" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_2A6EF9DFC104A0635E17770A1F47F252" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_963392D1FB515B511C01770A1F4C95B3_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_2A6EF9DFC104A0635E17770A1F47F252" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_963392D1FB515B511C01770A1F4C95B3_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_963392D1FB515B511C01770A1F4C95B3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_2A6EF9DFC104A0635E17770A1F47F252" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_963392D1FB515B511C01770A1F4C95B3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ForeignCountryMember" xlink:label="loc_us-gaap_ForeignCountryMember_F9645016B9C6DA073372770B0AA596D8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_963392D1FB515B511C01770A1F4C95B3" xlink:to="loc_us-gaap_ForeignCountryMember_F9645016B9C6DA073372770B0AA596D8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_2540E6859CC3AD0ED96176F98A23D67B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_AD2C85762834339E977F770A1F571B0C" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_2540E6859CC3AD0ED96176F98A23D67B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:label="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_E055B0FCB49F1ECD41D876F98A23C37C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_AD2C85762834339E977F770A1F571B0C" xlink:to="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_E055B0FCB49F1ECD41D876F98A23C37C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible" xlink:label="loc_us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible_19E368D4ACAFE75BD61F770A7E484BB6" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_AD2C85762834339E977F770A1F571B0C" xlink:to="loc_us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible_19E368D4ACAFE75BD61F770A7E484BB6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnrecognizedTaxBenefits" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_9ED7C639F04C3EBD0FFE76F98A230A32" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_AD2C85762834339E977F770A1F571B0C" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_9ED7C639F04C3EBD0FFE76F98A230A32" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.amkor.com/role/InterimFinancialStatements" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/InterimFinancialStatementsDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/InterimFinancialStatementsPolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/Leases" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/LeasesComponentsOfLeaseExpenseDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_C4C218E0E6DE6D0D04E26B9C90E656D3" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_8DE13983F045D284BDB06B9C90E5769A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_C4C218E0E6DE6D0D04E26B9C90E656D3" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_8DE13983F045D284BDB06B9C90E5769A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_F14F63699696FB4E1C8C6B9C90E5CEF8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_8DE13983F045D284BDB06B9C90E5769A" xlink:to="loc_srt_RangeAxis_F14F63699696FB4E1C8C6B9C90E5CEF8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_54C482A4C3E9900FFE6B6B9C90E65B68_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_F14F63699696FB4E1C8C6B9C90E5CEF8" xlink:to="loc_srt_RangeMember_54C482A4C3E9900FFE6B6B9C90E65B68_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_54C482A4C3E9900FFE6B6B9C90E65B68" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_F14F63699696FB4E1C8C6B9C90E5CEF8" xlink:to="loc_srt_RangeMember_54C482A4C3E9900FFE6B6B9C90E65B68" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_EA073182A9E008A61A826BB3E24AC2BD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_54C482A4C3E9900FFE6B6B9C90E65B68" xlink:to="loc_srt_MinimumMember_EA073182A9E008A61A826BB3E24AC2BD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_842B633E2414FC4414C16B9C90E60DB6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_54C482A4C3E9900FFE6B6B9C90E65B68" xlink:to="loc_srt_MaximumMember_842B633E2414FC4414C16B9C90E60DB6" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_LeaseRemainingLeaseTerm" xlink:label="loc_amkr_LeaseRemainingLeaseTerm_D818F2AB0908C39881386B9C90E772E1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_C4C218E0E6DE6D0D04E26B9C90E656D3" xlink:to="loc_amkr_LeaseRemainingLeaseTerm_D818F2AB0908C39881386B9C90E772E1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseCost" xlink:label="loc_us-gaap_OperatingLeaseCost_9296E74DB8141BCE435D6B9C90EC1CA6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_C4C218E0E6DE6D0D04E26B9C90E656D3" xlink:to="loc_us-gaap_OperatingLeaseCost_9296E74DB8141BCE435D6B9C90EC1CA6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseRightOfUseAssetAmortization" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_441081AEE3E1BF3A9C396B9C90EC3F47" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_C4C218E0E6DE6D0D04E26B9C90E656D3" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_441081AEE3E1BF3A9C396B9C90EC3F47" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseInterestExpense" xlink:label="loc_us-gaap_FinanceLeaseInterestExpense_CA49B1A3A615D81E00B86B9C90ECAE5D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_C4C218E0E6DE6D0D04E26B9C90E656D3" xlink:to="loc_us-gaap_FinanceLeaseInterestExpense_CA49B1A3A615D81E00B86B9C90ECAE5D" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_FinanceLeaseCost" xlink:label="loc_amkr_FinanceLeaseCost_606ED0F9424A097E47A76B9C90ECF6C3" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_C4C218E0E6DE6D0D04E26B9C90E656D3" xlink:to="loc_amkr_FinanceLeaseCost_606ED0F9424A097E47A76B9C90ECF6C3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LeaseCost" xlink:label="loc_us-gaap_LeaseCost_C026418C774265D645106B9C90ED1CEF" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_C4C218E0E6DE6D0D04E26B9C90E656D3" xlink:to="loc_us-gaap_LeaseCost_C026418C774265D645106B9C90ED1CEF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LeaseAndRentalExpense" xlink:label="loc_us-gaap_LeaseAndRentalExpense_7C57DC0465276A6345DD6B9C90EDA9FB" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_C4C218E0E6DE6D0D04E26B9C90E656D3" xlink:to="loc_us-gaap_LeaseAndRentalExpense_7C57DC0465276A6345DD6B9C90EDA9FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasePayments" xlink:label="loc_us-gaap_OperatingLeasePayments_0749B561F5405AC67D566B9C90EDCD8D" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_C4C218E0E6DE6D0D04E26B9C90E656D3" xlink:to="loc_us-gaap_OperatingLeasePayments_0749B561F5405AC67D566B9C90EDCD8D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseInterestPaymentOnLiability" xlink:label="loc_us-gaap_FinanceLeaseInterestPaymentOnLiability_8B9692765236DF3F48686B9C90ED3F67" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_C4C218E0E6DE6D0D04E26B9C90E656D3" xlink:to="loc_us-gaap_FinanceLeaseInterestPaymentOnLiability_8B9692765236DF3F48686B9C90ED3F67" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeasePrincipalPayments" xlink:label="loc_us-gaap_FinanceLeasePrincipalPayments_E161B4E2B2D0FFEFF1C06B9C90ED842D" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_C4C218E0E6DE6D0D04E26B9C90E656D3" xlink:to="loc_us-gaap_FinanceLeasePrincipalPayments_E161B4E2B2D0FFEFF1C06B9C90ED842D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_EAD81DBD36698AB99C166B9C90EDEB17" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_C4C218E0E6DE6D0D04E26B9C90E656D3" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_EAD81DBD36698AB99C166B9C90EDEB17" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1" xlink:label="loc_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1_73B0F9C435A9987AC84D6B9C90EE1473" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_C4C218E0E6DE6D0D04E26B9C90E656D3" xlink:to="loc_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1_73B0F9C435A9987AC84D6B9C90EE1473" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_0078BECD4219798668D26B9C90EE3E02" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_C4C218E0E6DE6D0D04E26B9C90E656D3" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_0078BECD4219798668D26B9C90EE3E02" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent" xlink:label="loc_us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent_91F9BF062D405693C4616B9C90EE5657" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_C4C218E0E6DE6D0D04E26B9C90E656D3" xlink:to="loc_us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent_91F9BF062D405693C4616B9C90EE5657" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.amkor.com/role/LeasesFutureMinimumLeasePaymentsDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/LeasesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/NetSalesByProductGroupAndEndMarket" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/NetSalesByProductGroupAndEndMarketNetSalesByEndMarketDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_8FD18803F833DF85CAF1270705B8B7D7" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_A2D5292AF415FCB62122270705B51227" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_8FD18803F833DF85CAF1270705B8B7D7" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_A2D5292AF415FCB62122270705B51227" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_9DE78A4FCB03F1C4EE5C270705B59D2F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_A2D5292AF415FCB62122270705B51227" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_9DE78A4FCB03F1C4EE5C270705B59D2F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_04BC9330E1DEE9ED2698270705B61B8F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_9DE78A4FCB03F1C4EE5C270705B59D2F" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_04BC9330E1DEE9ED2698270705B61B8F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_04BC9330E1DEE9ED2698270705B61B8F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_9DE78A4FCB03F1C4EE5C270705B59D2F" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_04BC9330E1DEE9ED2698270705B61B8F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerMember" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_A7CADFE045114D2374D2270705B6C929" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_04BC9330E1DEE9ED2698270705B61B8F" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_A7CADFE045114D2374D2270705B6C929" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_AAEE19812706E686A850270705B6B745" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_A2D5292AF415FCB62122270705B51227" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_AAEE19812706E686A850270705B6B745" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_6BB90069F51A8547F79C270705B6F29E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_AAEE19812706E686A850270705B6B745" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_6BB90069F51A8547F79C270705B6F29E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_6BB90069F51A8547F79C270705B6F29E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_AAEE19812706E686A850270705B6B745" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_6BB90069F51A8547F79C270705B6F29E" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_DistributionChannelConcentrationRiskMember" xlink:label="loc_amkr_DistributionChannelConcentrationRiskMember_2675002E0AD4D77747CE270705B7BE34" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_6BB90069F51A8547F79C270705B6F29E" xlink:to="loc_amkr_DistributionChannelConcentrationRiskMember_2675002E0AD4D77747CE270705B7BE34" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelAxis" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelAxis_BEFB3D2141C40F07E201270705B7337E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_A2D5292AF415FCB62122270705B51227" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelAxis_BEFB3D2141C40F07E201270705B7337E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelDomain" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_363C0E065974868EB8EF270705B7A920_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_BEFB3D2141C40F07E201270705B7337E" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_363C0E065974868EB8EF270705B7A920_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelDomain" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_363C0E065974868EB8EF270705B7A920" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_BEFB3D2141C40F07E201270705B7337E" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_363C0E065974868EB8EF270705B7A920" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_SalesChannelCommunicationsMember" xlink:label="loc_amkr_SalesChannelCommunicationsMember_685A681AD9C41AE616B5270705B75D58" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_363C0E065974868EB8EF270705B7A920" xlink:to="loc_amkr_SalesChannelCommunicationsMember_685A681AD9C41AE616B5270705B75D58" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_SalesChannelAutomotiveIndustrialAndOtherMember" xlink:label="loc_amkr_SalesChannelAutomotiveIndustrialAndOtherMember_D80C7EA92E600FEFAD72270705B8EC8C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_363C0E065974868EB8EF270705B7A920" xlink:to="loc_amkr_SalesChannelAutomotiveIndustrialAndOtherMember_D80C7EA92E600FEFAD72270705B8EC8C" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_SalesChannelComputingMember" xlink:label="loc_amkr_SalesChannelComputingMember_E75FE91C56FFF52BAF7D270705B85310" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_363C0E065974868EB8EF270705B7A920" xlink:to="loc_amkr_SalesChannelComputingMember_E75FE91C56FFF52BAF7D270705B85310" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SalesChannelDirectlyToConsumerMember" xlink:label="loc_us-gaap_SalesChannelDirectlyToConsumerMember_D70992A89F18ADDF49BD270705B8CF5E" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_363C0E065974868EB8EF270705B7A920" xlink:to="loc_us-gaap_SalesChannelDirectlyToConsumerMember_D70992A89F18ADDF49BD270705B8CF5E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_4B1A8457C75FF8EA1531270705B8307E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_8FD18803F833DF85CAF1270705B8B7D7" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_4B1A8457C75FF8EA1531270705B8307E" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.amkor.com/role/NetSalesByProductGroupAndEndMarketNetSalesByProductGroupDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_85661D169495FFD4DA3B2707069E941C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_5E5329A2988255585ACA2707069C8D15" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_85661D169495FFD4DA3B2707069E941C" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_5E5329A2988255585ACA2707069C8D15" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="loc_srt_ProductOrServiceAxis_F93AB2CB35E55E11D0102707069D58DD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_5E5329A2988255585ACA2707069C8D15" xlink:to="loc_srt_ProductOrServiceAxis_F93AB2CB35E55E11D0102707069D58DD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_A89B10C29D470AEB0FBE2707069D65CC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_F93AB2CB35E55E11D0102707069D58DD" xlink:to="loc_srt_ProductsAndServicesDomain_A89B10C29D470AEB0FBE2707069D65CC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_A89B10C29D470AEB0FBE2707069D65CC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_F93AB2CB35E55E11D0102707069D58DD" xlink:to="loc_srt_ProductsAndServicesDomain_A89B10C29D470AEB0FBE2707069D65CC" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_AdvancedProductsMember" xlink:label="loc_amkr_AdvancedProductsMember_2168A8CBB4B78B2147202707069EABA0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_A89B10C29D470AEB0FBE2707069D65CC" xlink:to="loc_amkr_AdvancedProductsMember_2168A8CBB4B78B2147202707069EABA0" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_MainstreamProductsMember" xlink:label="loc_amkr_MainstreamProductsMember_0B1B3A42318A5F517E5D2707069EA95B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_A89B10C29D470AEB0FBE2707069D65CC" xlink:to="loc_amkr_MainstreamProductsMember_0B1B3A42318A5F517E5D2707069EA95B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_70CBA1470BE4FCEB9A642707069E53AF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_85661D169495FFD4DA3B2707069E941C" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_70CBA1470BE4FCEB9A642707069E53AF" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.amkor.com/role/NetSalesByProductGroupAndEndMarketTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/NewAccountingStandards" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/OtherIncomeAndExpense" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/OtherIncomeAndExpenseDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/OtherIncomeAndExpenseTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/PensionPlans" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/PensionPlansComponentsOfNetPeriodicPensionCostDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/PensionPlansSummaryOfDefinedContributionExpenseDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/PensionPlansTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/PropertyPlantAndEquipment" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/PropertyPlantAndEquipmentSummaryOfDepreciationExpenseDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.amkor.com/role/PropertyPlantAndEquipmentSummaryOfPropertyPlantAndEquipmentDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_386A5660BE992DD13F5E76F989FC552A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_A49A0D8B8CE7E401326676F989FA6A21" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_386A5660BE992DD13F5E76F989FC552A" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_A49A0D8B8CE7E401326676F989FA6A21" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_59D36529409FDCE5002676F989FA1E8C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_A49A0D8B8CE7E401326676F989FA6A21" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_59D36529409FDCE5002676F989FA1E8C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_69C5E5E9312AFD4494FE76F989FBE19B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_59D36529409FDCE5002676F989FA1E8C" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_69C5E5E9312AFD4494FE76F989FBE19B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_69C5E5E9312AFD4494FE76F989FBE19B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_59D36529409FDCE5002676F989FA1E8C" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_69C5E5E9312AFD4494FE76F989FBE19B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LandMember" xlink:label="loc_us-gaap_LandMember_A4BE0CAAFF2B2E85455276F989FBC39B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_69C5E5E9312AFD4494FE76F989FBE19B" xlink:to="loc_us-gaap_LandMember_A4BE0CAAFF2B2E85455276F989FBC39B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UseRightsMember" xlink:label="loc_us-gaap_UseRightsMember_5F8D4DE3E4F56D7C14CC76F989FB56DD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_69C5E5E9312AFD4494FE76F989FBE19B" xlink:to="loc_us-gaap_UseRightsMember_5F8D4DE3E4F56D7C14CC76F989FB56DD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BuildingAndBuildingImprovementsMember" xlink:label="loc_us-gaap_BuildingAndBuildingImprovementsMember_0D9CC0A68BA2313D94D676F989FBB708" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_69C5E5E9312AFD4494FE76F989FBE19B" xlink:to="loc_us-gaap_BuildingAndBuildingImprovementsMember_0D9CC0A68BA2313D94D676F989FBB708" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MachineryAndEquipmentMember" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_E102880551AE6A943B2A76F989FB8EFA" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_69C5E5E9312AFD4494FE76F989FBE19B" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_E102880551AE6A943B2A76F989FB8EFA" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_FinanceLeasedAssetsMember" xlink:label="loc_amkr_FinanceLeasedAssetsMember_611E836ED5E9C2FB7D0676FB3D23AD2C" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_69C5E5E9312AFD4494FE76F989FBE19B" xlink:to="loc_amkr_FinanceLeasedAssetsMember_611E836ED5E9C2FB7D0676FB3D23AD2C" xlink:type="arc" />
    <link:loc xlink:href="amkr-20190331.xsd#amkr_SoftwareAndComputerEquipmentMember" xlink:label="loc_amkr_SoftwareAndComputerEquipmentMember_DB7999683089F625234276F989FC1333" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_69C5E5E9312AFD4494FE76F989FBE19B" xlink:to="loc_amkr_SoftwareAndComputerEquipmentMember_DB7999683089F625234276F989FC1333" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_20324D302C5C2E809C0F76F989FC09E2" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_69C5E5E9312AFD4494FE76F989FBE19B" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_20324D302C5C2E809C0F76F989FC09E2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConstructionInProgressMember" xlink:label="loc_us-gaap_ConstructionInProgressMember_35CFC089FF62BB7FFC9F76F989FCF3D7" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_69C5E5E9312AFD4494FE76F989FBE19B" xlink:to="loc_us-gaap_ConstructionInProgressMember_35CFC089FF62BB7FFC9F76F989FCF3D7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_A34A8BA3405CAC58EE0176F989FC3DC1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_386A5660BE992DD13F5E76F989FC552A" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_A34A8BA3405CAC58EE0176F989FC3DC1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_BF57849AF3A799F8E15E76F989FD7C97" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_386A5660BE992DD13F5E76F989FC552A" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_BF57849AF3A799F8E15E76F989FD7C97" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_7FEAEB6C26B333AEA0D376F989FDC0AA" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_386A5660BE992DD13F5E76F989FC552A" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_7FEAEB6C26B333AEA0D376F989FDC0AA" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.amkor.com/role/PropertyPlantAndEquipmentTables" xlink:type="extended" />
</link:linkbase>
