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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019e3c98-db8f-73ce-9a0d-724678687867,g:0d22b9e7-d903-4435-a9f0-8addcd50b61a-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/StatementsofUnauditedCondensedConsolidatedChangesinEquityStatement" xlink:type="simple" xlink:href="clf-20260630.xsd#StatementsofUnauditedCondensedConsolidatedChangesinEquityStatement"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/StatementsofUnauditedCondensedConsolidatedChangesinEquityStatement" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e3c98-dd0a-7a5d-a474-deca095d15a6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e3c98-dd0a-70e9-92d2-73b33495826d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e3c98-dd0a-7a5d-a474-deca095d15a6" xlink:to="loc_us-gaap_StatementTable_019e3c98-dd0a-70e9-92d2-73b33495826d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e3c98-dd0a-745e-a86a-f9e9280d379a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e3c98-dd0a-70e9-92d2-73b33495826d" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e3c98-dd0a-745e-a86a-f9e9280d379a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e3c98-dd0a-745e-a86a-f9e9280d379a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e3c98-dd0a-745e-a86a-f9e9280d379a" xlink:to="loc_us-gaap_EquityComponentDomain_019e3c98-dd0a-745e-a86a-f9e9280d379a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e3c98-dd0a-7b5b-8959-56559dde3cf4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e3c98-dd0a-745e-a86a-f9e9280d379a" xlink:to="loc_us-gaap_EquityComponentDomain_019e3c98-dd0a-7b5b-8959-56559dde3cf4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019e3c98-dd0a-76fc-9d16-fc67d8d8e8dc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e3c98-dd0a-7b5b-8959-56559dde3cf4" xlink:to="loc_us-gaap_CommonStockMember_019e3c98-dd0a-76fc-9d16-fc67d8d8e8dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019e3c98-dd0a-7c41-97d6-458c2caa370a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e3c98-dd0a-7b5b-8959-56559dde3cf4" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019e3c98-dd0a-7c41-97d6-458c2caa370a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019e3c98-dd0a-7f44-b571-bdb705e3621b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e3c98-dd0a-7b5b-8959-56559dde3cf4" xlink:to="loc_us-gaap_RetainedEarningsMember_019e3c98-dd0a-7f44-b571-bdb705e3621b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_019e3c98-dd0a-755a-bc2f-40a595a912fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e3c98-dd0a-7b5b-8959-56559dde3cf4" xlink:to="loc_us-gaap_TreasuryStockCommonMember_019e3c98-dd0a-755a-bc2f-40a595a912fa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e3c98-dd0a-7a91-9f26-b202a777c4af" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e3c98-dd0a-7b5b-8959-56559dde3cf4" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e3c98-dd0a-7a91-9f26-b202a777c4af" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_019e3c98-dd0a-7104-af81-520f3096fd22" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e3c98-dd0a-7b5b-8959-56559dde3cf4" xlink:to="loc_us-gaap_NoncontrollingInterestMember_019e3c98-dd0a-7104-af81-520f3096fd22" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e3c98-dd0a-77ae-80b0-a261b834a522" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e3c98-dd0a-7a5d-a474-deca095d15a6" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e3c98-dd0a-77ae-80b0-a261b834a522" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019e3c98-dd0a-76f8-8591-386de6bd6cb6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e3c98-dd0a-77ae-80b0-a261b834a522" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_019e3c98-dd0a-76f8-8591-386de6bd6cb6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e3c98-dd0a-7b71-9d15-4d13bf270d2c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e3c98-dd0a-77ae-80b0-a261b834a522" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e3c98-dd0a-7b71-9d15-4d13bf270d2c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_019e3c98-dd0a-7909-910d-58ba190bca32" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e3c98-dd0a-77ae-80b0-a261b834a522" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_019e3c98-dd0a-7909-910d-58ba190bca32" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019e3c98-dd0a-7430-b0f5-afa798a93bdd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e3c98-dd0a-77ae-80b0-a261b834a522" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019e3c98-dd0a-7430-b0f5-afa798a93bdd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019e3c98-dd0a-7933-b298-4895c98a0830" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e3c98-dd0a-77ae-80b0-a261b834a522" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019e3c98-dd0a-7933-b298-4895c98a0830" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019e3c98-dd0a-760d-956e-1381c8af4343" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e3c98-dd0a-77ae-80b0-a261b834a522" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019e3c98-dd0a-760d-956e-1381c8af4343" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_NoncontrollingInterestOtherIncreaseOfNoncontrollingInterest_019f7f82-3e3a-708c-979d-929a7dc272ab" xlink:href="clf-20260630.xsd#clf_NoncontrollingInterestOtherIncreaseOfNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e3c98-dd0a-77ae-80b0-a261b834a522" xlink:to="loc_clf_NoncontrollingInterestOtherIncreaseOfNoncontrollingInterest_019f7f82-3e3a-708c-979d-929a7dc272ab" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_019e3c98-dd0a-7d12-b501-ba9efa256106" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e3c98-dd0a-77ae-80b0-a261b834a522" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_019e3c98-dd0a-7d12-b501-ba9efa256106" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019e3c98-dd0a-7f49-b971-4ac4daff9b4f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e3c98-dd0a-7cd0-a948-a033cca8361d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/BASISOFPRESENTATIONANDSIGNIFICANTACCOUNTINGPOLICIESDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#BASISOFPRESENTATIONANDSIGNIFICANTACCOUNTINGPOLICIESDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/BASISOFPRESENTATIONANDSIGNIFICANTACCOUNTINGPOLICIESDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e3c98-dd0a-72de-a6e2-3ed9c635bf86" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_019e3c98-dd0a-75ee-b5e0-9ff9ccc181bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e3c98-dd0a-72de-a6e2-3ed9c635bf86" xlink:to="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_019e3c98-dd0a-75ee-b5e0-9ff9ccc181bf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementAxis_019e3c98-dd0a-77e7-86dd-df8a0cd9db94" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RestatementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_019e3c98-dd0a-75ee-b5e0-9ff9ccc181bf" xlink:to="loc_srt_RestatementAxis_019e3c98-dd0a-77e7-86dd-df8a0cd9db94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementDomain_019e3c98-dd0a-77e7-86dd-df8a0cd9db94_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RestatementDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RestatementAxis_019e3c98-dd0a-77e7-86dd-df8a0cd9db94" xlink:to="loc_srt_RestatementDomain_019e3c98-dd0a-77e7-86dd-df8a0cd9db94_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementDomain_019e3c98-dd0a-7040-ab33-474885344ed9" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RestatementDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RestatementAxis_019e3c98-dd0a-77e7-86dd-df8a0cd9db94" xlink:to="loc_srt_RestatementDomain_019e3c98-dd0a-7040-ab33-474885344ed9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementAdjustmentMember_019e3c98-dd0a-7143-86a6-55b393fb9b25" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RestatementAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RestatementDomain_019e3c98-dd0a-7040-ab33-474885344ed9" xlink:to="loc_srt_RestatementAdjustmentMember_019e3c98-dd0a-7143-86a6-55b393fb9b25" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_019e3c98-dd0a-79b8-88c7-9177161e8095" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e3c98-dd0a-72de-a6e2-3ed9c635bf86" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_019e3c98-dd0a-79b8-88c7-9177161e8095" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019e3c98-dd0a-7241-af8c-cdda331eaa8b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e3c98-dd0a-72de-a6e2-3ed9c635bf86" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019e3c98-dd0a-7241-af8c-cdda331eaa8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_019e3c98-dd0a-72e6-b869-7272aae0962e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e3c98-dd0a-72de-a6e2-3ed9c635bf86" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_019e3c98-dd0a-72e6-b869-7272aae0962e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAndOtherLiabilitiesNoncurrent_019e3c98-dd0a-7c14-9688-deb844ba0a7d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAndOtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e3c98-dd0a-72de-a6e2-3ed9c635bf86" xlink:to="loc_us-gaap_DeferredTaxAndOtherLiabilitiesNoncurrent_019e3c98-dd0a-7c14-9688-deb844ba0a7d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019e3c98-dd0a-7bfa-baab-d79733042448" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e3c98-dd0a-72de-a6e2-3ed9c635bf86" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019e3c98-dd0a-7bfa-baab-d79733042448" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/SUPPLEMENTARYFINANCIALSTATEMENTINFORMATIONNarrativeDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#SUPPLEMENTARYFINANCIALSTATEMENTINFORMATIONNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/SUPPLEMENTARYFINANCIALSTATEMENTINFORMATIONNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplierFinanceProgramLineItems_019e3c98-dd0a-7a4d-b2bc-718c4ef6253a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplierFinanceProgramLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplierFinanceProgramTable_019e3c98-dd0a-76e4-8c5a-684b335026ad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplierFinanceProgramTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SupplierFinanceProgramLineItems_019e3c98-dd0a-7a4d-b2bc-718c4ef6253a" xlink:to="loc_us-gaap_SupplierFinanceProgramTable_019e3c98-dd0a-76e4-8c5a-684b335026ad" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_019e3c98-dd0a-73db-90e0-fceba73e86fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SupplierFinanceProgramTable_019e3c98-dd0a-76e4-8c5a-684b335026ad" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_019e3c98-dd0a-73db-90e0-fceba73e86fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_019e3c98-dd0a-73db-90e0-fceba73e86fb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_019e3c98-dd0a-73db-90e0-fceba73e86fb" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_019e3c98-dd0a-73db-90e0-fceba73e86fb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_019e3c98-dd0a-70a5-8231-1892aad40d1b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_019e3c98-dd0a-73db-90e0-fceba73e86fb" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_019e3c98-dd0a-70a5-8231-1892aad40d1b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCurrentLiabilitiesMember_019e3c98-dd0a-7d9b-a851-ae390a844c59" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_019e3c98-dd0a-70a5-8231-1892aad40d1b" xlink:to="loc_us-gaap_OtherCurrentLiabilitiesMember_019e3c98-dd0a-7d9b-a851-ae390a844c59" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableMember_019e3c98-dd0a-7c22-b0a6-8d35e19a334a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsPayableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_019e3c98-dd0a-70a5-8231-1892aad40d1b" xlink:to="loc_us-gaap_AccountsPayableMember_019e3c98-dd0a-7c22-b0a6-8d35e19a334a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplierFinanceProgramObligationCurrent_019e3c98-dd0a-781b-a878-b2f5ac1f1212" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplierFinanceProgramObligationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplierFinanceProgramLineItems_019e3c98-dd0a-7a4d-b2bc-718c4ef6253a" xlink:to="loc_us-gaap_SupplierFinanceProgramObligationCurrent_019e3c98-dd0a-781b-a878-b2f5ac1f1212" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/SUPPLEMENTARYFINANCIALSTATEMENTINFORMATIONRestructuringDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#SUPPLEMENTARYFINANCIALSTATEMENTINFORMATIONRestructuringDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/SUPPLEMENTARYFINANCIALSTATEMENTINFORMATIONRestructuringDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019e3c98-dd0a-7397-bfbc-5cca8721ab7a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e3c98-dd0a-71d2-848f-023a624ea161" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e3c98-dd0a-7397-bfbc-5cca8721ab7a" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e3c98-dd0a-71d2-848f-023a624ea161" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019e3c98-dd0a-79ba-b58d-3aeb1dff482b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e3c98-dd0a-71d2-848f-023a624ea161" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019e3c98-dd0a-79ba-b58d-3aeb1dff482b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e3c98-dd0a-79ba-b58d-3aeb1dff482b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e3c98-dd0a-79ba-b58d-3aeb1dff482b" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e3c98-dd0a-79ba-b58d-3aeb1dff482b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e3c98-dd0a-7538-bf54-a9afceba4110" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e3c98-dd0a-79ba-b58d-3aeb1dff482b" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e3c98-dd0a-7538-bf54-a9afceba4110" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeSeveranceMember_019e3c98-dd0a-73b5-85e1-47061791d420" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeSeveranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019e3c98-dd0a-7538-bf54-a9afceba4110" xlink:to="loc_us-gaap_EmployeeSeveranceMember_019e3c98-dd0a-73b5-85e1-47061791d420" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherRestructuringMember_019e3c98-dd0a-7925-93fa-696a124f91f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherRestructuringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019e3c98-dd0a-7538-bf54-a9afceba4110" xlink:to="loc_us-gaap_OtherRestructuringMember_019e3c98-dd0a-7925-93fa-696a124f91f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_019e3c98-dd0a-7487-951e-76965c87c4f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e3c98-dd0a-71d2-848f-023a624ea161" xlink:to="loc_us-gaap_RestructuringPlanAxis_019e3c98-dd0a-7487-951e-76965c87c4f9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e3c98-dd0a-7487-951e-76965c87c4f9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e3c98-dd0a-7487-951e-76965c87c4f9" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e3c98-dd0a-7487-951e-76965c87c4f9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e3c98-dd0a-775b-a9d9-801661417545" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e3c98-dd0a-7487-951e-76965c87c4f9" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e3c98-dd0a-775b-a9d9-801661417545" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherRestructuringMember_019e3c98-dd0a-78c4-b9d4-70719ddc1f22" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherRestructuringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_019e3c98-dd0a-775b-a9d9-801661417545" xlink:to="loc_us-gaap_OtherRestructuringMember_019e3c98-dd0a-78c4-b9d4-70719ddc1f22" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_019e3c98-dd0a-73ac-8d15-002f2c5fedce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserve"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e3c98-dd0a-7397-bfbc-5cca8721ab7a" xlink:to="loc_us-gaap_RestructuringReserve_019e3c98-dd0a-73ac-8d15-002f2c5fedce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringSettlementAndImpairmentProvisions_019f619f-37f5-7a08-882c-70a9ccd2d5f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringSettlementAndImpairmentProvisions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e3c98-dd0a-7397-bfbc-5cca8721ab7a" xlink:to="loc_us-gaap_RestructuringSettlementAndImpairmentProvisions_019f619f-37f5-7a08-882c-70a9ccd2d5f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRestructuring_019e3c98-dd0a-7ade-b67f-9cfa1d5da4a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForRestructuring"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e3c98-dd0a-7397-bfbc-5cca8721ab7a" xlink:to="loc_us-gaap_PaymentsForRestructuring_019e3c98-dd0a-7ade-b67f-9cfa1d5da4a2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_019e3c98-dd0a-7f24-abe9-45aa996bb0f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserve"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/REVENUESRevenuesByMarketDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#REVENUESRevenuesByMarketDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/REVENUESRevenuesByMarketDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019e3c98-dd0a-719d-ba9c-3458a763fdcf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019e3c98-dd0a-7437-8012-8852685dc6ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e3c98-dd0a-719d-ba9c-3458a763fdcf" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019e3c98-dd0a-7437-8012-8852685dc6ff" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesByIndustryAxis_019e3c98-dd0a-7ac9-bd3c-ab453ead17e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesByIndustryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e3c98-dd0a-7437-8012-8852685dc6ff" xlink:to="loc_us-gaap_EquitySecuritiesByIndustryAxis_019e3c98-dd0a-7ac9-bd3c-ab453ead17e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_019e3c98-dd0a-7ac9-bd3c-ab453ead17e2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_019e3c98-dd0a-7ac9-bd3c-ab453ead17e2" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_019e3c98-dd0a-7ac9-bd3c-ab453ead17e2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_019e3c98-dd0a-7f24-9d03-9ab3d6c44354" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_019e3c98-dd0a-7ac9-bd3c-ab453ead17e2" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_019e3c98-dd0a-7f24-9d03-9ab3d6c44354" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_AutomotiveMember_019e3c98-dd0a-7e9b-8ac5-9bf13643188a" xlink:href="clf-20260630.xsd#clf_AutomotiveMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_019e3c98-dd0a-7f24-9d03-9ab3d6c44354" xlink:to="loc_clf_AutomotiveMember_019e3c98-dd0a-7e9b-8ac5-9bf13643188a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_InfrastructureAndManufacturingMember_019e3c98-dd0a-706a-baf1-c9e5e77616f2" xlink:href="clf-20260630.xsd#clf_InfrastructureAndManufacturingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_019e3c98-dd0a-7f24-9d03-9ab3d6c44354" xlink:to="loc_clf_InfrastructureAndManufacturingMember_019e3c98-dd0a-706a-baf1-c9e5e77616f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_DistributorsAndConvertersMember_019e3c98-dd0a-7861-b6ab-6e9823608031" xlink:href="clf-20260630.xsd#clf_DistributorsAndConvertersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_019e3c98-dd0a-7f24-9d03-9ab3d6c44354" xlink:to="loc_clf_DistributorsAndConvertersMember_019e3c98-dd0a-7861-b6ab-6e9823608031" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_SteelProducersMember_019e3c98-dd0a-7a30-919b-aabf31743702" xlink:href="clf-20260630.xsd#clf_SteelProducersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_019e3c98-dd0a-7f24-9d03-9ab3d6c44354" xlink:to="loc_clf_SteelProducersMember_019e3c98-dd0a-7a30-919b-aabf31743702" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-7d4b-9fef-566fe4466d36" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e3c98-dd0a-7437-8012-8852685dc6ff" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-7d4b-9fef-566fe4466d36" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7d4b-9fef-566fe4466d36_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-7d4b-9fef-566fe4466d36" xlink:to="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7d4b-9fef-566fe4466d36_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e3c98-dd0a-75b3-b929-fed85b1278e3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-7d4b-9fef-566fe4466d36" xlink:to="loc_us-gaap_SegmentDomain_019e3c98-dd0a-75b3-b929-fed85b1278e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_SteelmakingMember_019e3c98-dd0a-74b1-b031-89d0258556b9" xlink:href="clf-20260630.xsd#clf_SteelmakingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e3c98-dd0a-75b3-b929-fed85b1278e3" xlink:to="loc_clf_SteelmakingMember_019e3c98-dd0a-74b1-b031-89d0258556b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_OtherBusinessesMember_019e3c98-dd0a-77a6-ac42-e1bddb63e39d" xlink:href="clf-20260630.xsd#clf_OtherBusinessesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e3c98-dd0a-75b3-b929-fed85b1278e3" xlink:to="loc_clf_OtherBusinessesMember_019e3c98-dd0a-77a6-ac42-e1bddb63e39d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019e3c98-dd0a-793a-82ce-2c5182d48daa" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e3c98-dd0a-7437-8012-8852685dc6ff" xlink:to="loc_srt_MajorCustomersAxis_019e3c98-dd0a-793a-82ce-2c5182d48daa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019e3c98-dd0a-793a-82ce-2c5182d48daa_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_019e3c98-dd0a-793a-82ce-2c5182d48daa" xlink:to="loc_srt_NameOfMajorCustomerDomain_019e3c98-dd0a-793a-82ce-2c5182d48daa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019e3c98-dd0a-7a52-9910-6ad26a9792e3" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_019e3c98-dd0a-793a-82ce-2c5182d48daa" xlink:to="loc_srt_NameOfMajorCustomerDomain_019e3c98-dd0a-7a52-9910-6ad26a9792e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_ThirdPartyMember_019e3c98-dd0a-7d78-b89f-aec4a57cfc73" xlink:href="clf-20260630.xsd#clf_ThirdPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019e3c98-dd0a-7a52-9910-6ad26a9792e3" xlink:to="loc_clf_ThirdPartyMember_019e3c98-dd0a-7d78-b89f-aec4a57cfc73" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019e3c98-dd0a-76f3-8bcf-668b46064601" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e3c98-dd0a-719d-ba9c-3458a763fdcf" xlink:to="loc_us-gaap_Revenues_019e3c98-dd0a-76f3-8bcf-668b46064601" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/REVENUESRevenuesByProductLineDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#REVENUESRevenuesByProductLineDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/REVENUESRevenuesByProductLineDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019e3c98-dd0a-7be2-b613-c4ab1e94c328" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019e3c98-dd0a-72e7-9104-b54ca17452a6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e3c98-dd0a-7be2-b613-c4ab1e94c328" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019e3c98-dd0a-72e7-9104-b54ca17452a6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-71be-8067-ffdb973b2ac6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e3c98-dd0a-72e7-9104-b54ca17452a6" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-71be-8067-ffdb973b2ac6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e3c98-dd0a-71be-8067-ffdb973b2ac6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-71be-8067-ffdb973b2ac6" xlink:to="loc_us-gaap_SegmentDomain_019e3c98-dd0a-71be-8067-ffdb973b2ac6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7788-8691-cbd1ef15237f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-71be-8067-ffdb973b2ac6" xlink:to="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7788-8691-cbd1ef15237f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_SteelmakingMember_019e3c98-dd0a-79a7-8a40-ce59e551e42e" xlink:href="clf-20260630.xsd#clf_SteelmakingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7788-8691-cbd1ef15237f" xlink:to="loc_clf_SteelmakingMember_019e3c98-dd0a-79a7-8a40-ce59e551e42e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_OtherBusinessesMember_019e3c98-dd0a-7464-9dbc-78b886228b41" xlink:href="clf-20260630.xsd#clf_OtherBusinessesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7788-8691-cbd1ef15237f" xlink:to="loc_clf_OtherBusinessesMember_019e3c98-dd0a-7464-9dbc-78b886228b41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019e3c98-dd0a-7480-8b91-cce544eb5372" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e3c98-dd0a-72e7-9104-b54ca17452a6" xlink:to="loc_srt_ProductOrServiceAxis_019e3c98-dd0a-7480-8b91-cce544eb5372" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e3c98-dd0a-7480-8b91-cce544eb5372_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019e3c98-dd0a-7480-8b91-cce544eb5372" xlink:to="loc_srt_ProductsAndServicesDomain_019e3c98-dd0a-7480-8b91-cce544eb5372_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e3c98-dd0a-7174-bc41-38664d8b1c6e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019e3c98-dd0a-7480-8b91-cce544eb5372" xlink:to="loc_srt_ProductsAndServicesDomain_019e3c98-dd0a-7174-bc41-38664d8b1c6e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_HotRolledSteelMember_019e3c98-dd0a-7611-9724-0a065ab2c929" xlink:href="clf-20260630.xsd#clf_HotRolledSteelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e3c98-dd0a-7174-bc41-38664d8b1c6e" xlink:to="loc_clf_HotRolledSteelMember_019e3c98-dd0a-7611-9724-0a065ab2c929" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_ColdRolledSteelMember_019e3c98-dd0a-7308-b404-7a12ae23c21a" xlink:href="clf-20260630.xsd#clf_ColdRolledSteelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e3c98-dd0a-7174-bc41-38664d8b1c6e" xlink:to="loc_clf_ColdRolledSteelMember_019e3c98-dd0a-7308-b404-7a12ae23c21a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_CoatedSteelMember_019e3c98-dd0a-7f07-970b-f0e2b7e3d41b" xlink:href="clf-20260630.xsd#clf_CoatedSteelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e3c98-dd0a-7174-bc41-38664d8b1c6e" xlink:to="loc_clf_CoatedSteelMember_019e3c98-dd0a-7f07-970b-f0e2b7e3d41b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_StainlessAndElectricalSteelMember_019e3c98-dd0a-75b0-8375-eda3ad3c83e4" xlink:href="clf-20260630.xsd#clf_StainlessAndElectricalSteelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e3c98-dd0a-7174-bc41-38664d8b1c6e" xlink:to="loc_clf_StainlessAndElectricalSteelMember_019e3c98-dd0a-75b0-8375-eda3ad3c83e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_PlateSteelMember_019e3c98-dd0a-7316-8ae9-dfdc250d9ad6" xlink:href="clf-20260630.xsd#clf_PlateSteelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e3c98-dd0a-7174-bc41-38664d8b1c6e" xlink:to="loc_clf_PlateSteelMember_019e3c98-dd0a-7316-8ae9-dfdc250d9ad6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_OtherSteelProductsMember_019e3c98-dd0a-780f-b29b-e73ea1838eeb" xlink:href="clf-20260630.xsd#clf_OtherSteelProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e3c98-dd0a-7174-bc41-38664d8b1c6e" xlink:to="loc_clf_OtherSteelProductsMember_019e3c98-dd0a-780f-b29b-e73ea1838eeb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_OtherMember_019e3c98-dd0a-72ff-a17b-b4f3a33ae04f" xlink:href="clf-20260630.xsd#clf_OtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e3c98-dd0a-7174-bc41-38664d8b1c6e" xlink:to="loc_clf_OtherMember_019e3c98-dd0a-72ff-a17b-b4f3a33ae04f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019e3c98-dd0a-7305-916e-9e1ef4cbbbfa" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e3c98-dd0a-72e7-9104-b54ca17452a6" xlink:to="loc_srt_MajorCustomersAxis_019e3c98-dd0a-7305-916e-9e1ef4cbbbfa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019e3c98-dd0a-7305-916e-9e1ef4cbbbfa_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_019e3c98-dd0a-7305-916e-9e1ef4cbbbfa" xlink:to="loc_srt_NameOfMajorCustomerDomain_019e3c98-dd0a-7305-916e-9e1ef4cbbbfa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019e3c98-dd0a-705e-bbdc-9ed48df3ba68" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_019e3c98-dd0a-7305-916e-9e1ef4cbbbfa" xlink:to="loc_srt_NameOfMajorCustomerDomain_019e3c98-dd0a-705e-bbdc-9ed48df3ba68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_ThirdPartyMember_019e3c98-dd0a-7f21-a5ad-e37444058fda" xlink:href="clf-20260630.xsd#clf_ThirdPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019e3c98-dd0a-705e-bbdc-9ed48df3ba68" xlink:to="loc_clf_ThirdPartyMember_019e3c98-dd0a-7f21-a5ad-e37444058fda" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019e3c98-dd0a-724e-b29c-9a6c9dc2027c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e3c98-dd0a-7be2-b613-c4ab1e94c328" xlink:to="loc_us-gaap_Revenues_019e3c98-dd0a-724e-b29c-9a6c9dc2027c" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/SEGMENTREPORTINGEBITDAReconciliationandCapitalAdditionsDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#SEGMENTREPORTINGEBITDAReconciliationandCapitalAdditionsDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/SEGMENTREPORTINGEBITDAReconciliationandCapitalAdditionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e3c98-dd0a-7fdc-8f16-ffd517b9a80b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e3c98-dd0a-7fdc-8f16-ffd517b9a80b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-7491-96f1-2717c57b95c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e3c98-dd0a-7fdc-8f16-ffd517b9a80b" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-7491-96f1-2717c57b95c3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7491-96f1-2717c57b95c3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-7491-96f1-2717c57b95c3" xlink:to="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7491-96f1-2717c57b95c3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e3c98-dd0a-73d2-930d-c1c5a64b52dd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-7491-96f1-2717c57b95c3" xlink:to="loc_us-gaap_SegmentDomain_019e3c98-dd0a-73d2-930d-c1c5a64b52dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_SteelmakingMember_019e3c98-dd0a-774c-99e7-0d3ffaddfb4d" xlink:href="clf-20260630.xsd#clf_SteelmakingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e3c98-dd0a-73d2-930d-c1c5a64b52dd" xlink:to="loc_clf_SteelmakingMember_019e3c98-dd0a-774c-99e7-0d3ffaddfb4d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_OtherBusinessesMember_019e3c98-dd0a-74ea-9847-77b08ae8462e" xlink:href="clf-20260630.xsd#clf_OtherBusinessesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e3c98-dd0a-73d2-930d-c1c5a64b52dd" xlink:to="loc_clf_OtherBusinessesMember_019e3c98-dd0a-74ea-9847-77b08ae8462e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_EliminationsMember_019e3c98-dd0a-744e-b1ae-087c90993589" xlink:href="clf-20260630.xsd#clf_EliminationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e3c98-dd0a-73d2-930d-c1c5a64b52dd" xlink:to="loc_clf_EliminationsMember_019e3c98-dd0a-744e-b1ae-087c90993589" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_AdjEBITDACalculationAxis_019e3c98-dd0a-71ed-862f-293c45674a2d" xlink:href="clf-20260630.xsd#clf_AdjEBITDACalculationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e3c98-dd0a-7fdc-8f16-ffd517b9a80b" xlink:to="loc_clf_AdjEBITDACalculationAxis_019e3c98-dd0a-71ed-862f-293c45674a2d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_AdjEBITDACalculationDomain_019e3c98-dd0a-71ed-862f-293c45674a2d_default" xlink:href="clf-20260630.xsd#clf_AdjEBITDACalculationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_clf_AdjEBITDACalculationAxis_019e3c98-dd0a-71ed-862f-293c45674a2d" xlink:to="loc_clf_AdjEBITDACalculationDomain_019e3c98-dd0a-71ed-862f-293c45674a2d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_AdjEBITDACalculationDomain_019e3c98-dd0a-7d85-8e40-3574115cea7c" xlink:href="clf-20260630.xsd#clf_AdjEBITDACalculationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_clf_AdjEBITDACalculationAxis_019e3c98-dd0a-71ed-862f-293c45674a2d" xlink:to="loc_clf_AdjEBITDACalculationDomain_019e3c98-dd0a-7d85-8e40-3574115cea7c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_AdjEBITDACalculationMember_019e3c98-dd0a-7676-9495-b888c18d046c" xlink:href="clf-20260630.xsd#clf_AdjEBITDACalculationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_clf_AdjEBITDACalculationDomain_019e3c98-dd0a-7d85-8e40-3574115cea7c" xlink:to="loc_clf_AdjEBITDACalculationMember_019e3c98-dd0a-7676-9495-b888c18d046c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019e3c98-dd0a-7c95-b098-4abc71169a95" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_us-gaap_Revenues_019e3c98-dd0a-7c95-b098-4abc71169a95" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_019e3c98-dd0a-7fee-b38d-a8b3f5ab9ec0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_019e3c98-dd0a-7fee-b38d-a8b3f5ab9ec0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019e3c98-dd0a-7a08-89ca-3233fcaafc43" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019e3c98-dd0a-7a08-89ca-3233fcaafc43" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_019e3c98-dd0a-702f-8c78-4aa66b0f89f1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_019e3c98-dd0a-702f-8c78-4aa66b0f89f1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_019e3c98-dd0a-77fd-9c62-bbc4308ac470" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_019e3c98-dd0a-77fd-9c62-bbc4308ac470" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_019e3c98-dd0a-75ee-9118-b4f49cac42f3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherItemAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_019e3c98-dd0a-75ee-9118-b4f49cac42f3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_AdjustedEBITDAEarningsLoss_019e3c98-dd0a-75be-819d-40e97f424eef" xlink:href="clf-20260630.xsd#clf_AdjustedEBITDAEarningsLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_clf_AdjustedEBITDAEarningsLoss_019e3c98-dd0a-75be-819d-40e97f424eef" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseNonoperatingNet_019e3c98-dd0a-7973-82ee-558e7d9106ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestIncomeExpenseNonoperatingNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_us-gaap_InterestIncomeExpenseNonoperatingNet_019e3c98-dd0a-7973-82ee-558e7d9106ed" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019e3c98-dd0a-7a7b-b8eb-015422b3bf6d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019e3c98-dd0a-7a7b-b8eb-015422b3bf6d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_019e3c98-dd0a-7973-8fc0-70a9237e4055" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_EBITDAOfNoncontrollingInterests_019e3c98-dd0a-71ce-9d62-d1933502cf86" xlink:href="clf-20260630.xsd#clf_EBITDAOfNoncontrollingInterests"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_clf_EBITDAOfNoncontrollingInterests_019e3c98-dd0a-71ce-9d62-d1933502cf86" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_IdledFacilitiesCharges_019e3c98-dd0a-7dce-8207-475790c99e03" xlink:href="clf-20260630.xsd#clf_IdledFacilitiesCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_clf_IdledFacilitiesCharges_019e3c98-dd0a-7dce-8207-475790c99e03" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_019e3c98-dd0a-7e4e-9c5d-ee06b970fd2b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_019e3c98-dd0a-7e4e-9c5d-ee06b970fd2b" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_019e3c98-dd0a-754b-8693-5fc1b5f2156a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_019e3c98-dd0a-754b-8693-5fc1b5f2156a" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_AmortizationOfInventoryStepUp_019e3c98-dd0a-7d0f-bf35-f7a1c7042cba" xlink:href="clf-20260630.xsd#clf_AmortizationOfInventoryStepUp"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_clf_AmortizationOfInventoryStepUp_019e3c98-dd0a-7d0f-bf35-f7a1c7042cba" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_OtherAdjustmentsNet_019e3c98-dd0a-7aa6-a968-21add83d5081" xlink:href="clf-20260630.xsd#clf_OtherAdjustmentsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_clf_OtherAdjustmentsNet_019e3c98-dd0a-7aa6-a968-21add83d5081" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019e3c98-dd0a-7a2b-8370-c585e90eb3a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_us-gaap_ProfitLoss_019e3c98-dd0a-7a2b-8370-c585e90eb3a4" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_019e3c98-dd0a-741e-bf4f-678142e4145f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentExpenditureAdditionToLongLivedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_019e3c98-dd0a-741e-bf4f-678142e4145f" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019e3c98-dd0a-742b-9e3c-aca4b757b7b6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019e3c98-dd0a-742b-9e3c-aca4b757b7b6" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_DepreciationDepletionAndAmortizationAttributableToNoncontrollingInterests_019e3c98-dd0a-75e4-b310-32c9cf5d527a" xlink:href="clf-20260630.xsd#clf_DepreciationDepletionAndAmortizationAttributableToNoncontrollingInterests"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_clf_DepreciationDepletionAndAmortizationAttributableToNoncontrollingInterests_019e3c98-dd0a-75e4-b310-32c9cf5d527a" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfOtherAssets_019edae5-8a7f-7db8-b81f-9b33f9a310be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnSaleOfOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_us-gaap_GainLossOnSaleOfOtherAssets_019edae5-8a7f-7db8-b81f-9b33f9a310be" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeveranceCosts1_019f436e-3476-762a-aa9d-7dd4c94547c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeveranceCosts1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e3c98-dd0a-7041-b65e-4c5c3747f77d" xlink:to="loc_us-gaap_SeveranceCosts1_019f436e-3476-762a-aa9d-7dd4c94547c3" xlink:type="arc" order="21"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/SEGMENTREPORTINGSummaryofAssetsbySegmentDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#SEGMENTREPORTINGSummaryofAssetsbySegmentDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/SEGMENTREPORTINGSummaryofAssetsbySegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_019e3c98-dd0a-7f3f-b415-e7e6a5c9f5fd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingAssetReconcilingItemLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_019e3c98-dd0a-702f-94c6-037075d82c04" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_019e3c98-dd0a-7f3f-b415-e7e6a5c9f5fd" xlink:to="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_019e3c98-dd0a-702f-94c6-037075d82c04" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-7850-8b88-efb52f666bd5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_019e3c98-dd0a-702f-94c6-037075d82c04" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-7850-8b88-efb52f666bd5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7850-8b88-efb52f666bd5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-7850-8b88-efb52f666bd5" xlink:to="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7850-8b88-efb52f666bd5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7363-a2cc-10046e0a7b9b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-7850-8b88-efb52f666bd5" xlink:to="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7363-a2cc-10046e0a7b9b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_SteelmakingMember_019e3c98-dd0a-7c94-83c8-ded6681b5e65" xlink:href="clf-20260630.xsd#clf_SteelmakingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7363-a2cc-10046e0a7b9b" xlink:to="loc_clf_SteelmakingMember_019e3c98-dd0a-7c94-83c8-ded6681b5e65" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_OtherBusinessesMember_019e3c98-dd0a-7171-b210-b829c91f09d9" xlink:href="clf-20260630.xsd#clf_OtherBusinessesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7363-a2cc-10046e0a7b9b" xlink:to="loc_clf_OtherBusinessesMember_019e3c98-dd0a-7171-b210-b829c91f09d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019e3c98-dd0a-72b8-aeac-06ef3a95bc11" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_019e3c98-dd0a-7f3f-b415-e7e6a5c9f5fd" xlink:to="loc_us-gaap_Assets_019e3c98-dd0a-72b8-aeac-06ef3a95bc11" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/PROPERTYPLANTANDEQUIPMENTDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#PROPERTYPLANTANDEQUIPMENTDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/PROPERTYPLANTANDEQUIPMENTDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e3c98-dd0a-71cf-b5bc-cde12d2dd33d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019e3c98-dd0a-7e92-8bd7-736b46378e38" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e3c98-dd0a-71cf-b5bc-cde12d2dd33d" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019e3c98-dd0a-7e92-8bd7-736b46378e38" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e3c98-dd0a-7407-91ba-106707186be8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019e3c98-dd0a-7e92-8bd7-736b46378e38" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e3c98-dd0a-7407-91ba-106707186be8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e3c98-dd0a-7407-91ba-106707186be8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e3c98-dd0a-7407-91ba-106707186be8" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e3c98-dd0a-7407-91ba-106707186be8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e3c98-dd0a-7ddc-b11d-6cda7357a888" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e3c98-dd0a-7407-91ba-106707186be8" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e3c98-dd0a-7ddc-b11d-6cda7357a888" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_LandlandimprovementsandmineralrightsMember_019e3c98-dd0a-7dc5-a09c-b6687f2936cd" xlink:href="clf-20260630.xsd#clf_LandlandimprovementsandmineralrightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e3c98-dd0a-7ddc-b11d-6cda7357a888" xlink:to="loc_clf_LandlandimprovementsandmineralrightsMember_019e3c98-dd0a-7dc5-a09c-b6687f2936cd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingMember_019e3c98-dd0a-7d54-9fee-7897d902f08e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e3c98-dd0a-7ddc-b11d-6cda7357a888" xlink:to="loc_us-gaap_BuildingMember_019e3c98-dd0a-7d54-9fee-7897d902f08e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquipmentMember_019e3c98-dd0a-734e-96ee-ac8a2b19679e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e3c98-dd0a-7ddc-b11d-6cda7357a888" xlink:to="loc_us-gaap_EquipmentMember_019e3c98-dd0a-734e-96ee-ac8a2b19679e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCapitalizedPropertyPlantAndEquipmentMember_019e3c98-dd0a-7f5b-ac07-d49cbe7b52cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCapitalizedPropertyPlantAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e3c98-dd0a-7ddc-b11d-6cda7357a888" xlink:to="loc_us-gaap_OtherCapitalizedPropertyPlantAndEquipmentMember_019e3c98-dd0a-7f5b-ac07-d49cbe7b52cc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_019e3c98-dd0a-7d11-8f9a-87feccb3490f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e3c98-dd0a-7ddc-b11d-6cda7357a888" xlink:to="loc_us-gaap_ConstructionInProgressMember_019e3c98-dd0a-7d11-8f9a-87feccb3490f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_019e3c98-dd0a-75b9-b6a6-10aa75f4da93" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e3c98-dd0a-71cf-b5bc-cde12d2dd33d" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_019e3c98-dd0a-75b9-b6a6-10aa75f4da93" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019e3c98-dd0a-7def-a655-f672d1493199" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e3c98-dd0a-71cf-b5bc-cde12d2dd33d" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019e3c98-dd0a-7def-a655-f672d1493199" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019e3c98-dd0a-7726-9db7-11d3848bf849" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e3c98-dd0a-71cf-b5bc-cde12d2dd33d" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019e3c98-dd0a-7726-9db7-11d3848bf849" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization_019e3c98-dd0a-7903-8320-f5220baa5f85" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e3c98-dd0a-71cf-b5bc-cde12d2dd33d" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization_019e3c98-dd0a-7903-8320-f5220baa5f85" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_019e3c98-dd0a-7973-9606-829185e68770" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e3c98-dd0a-71cf-b5bc-cde12d2dd33d" xlink:to="loc_us-gaap_Depreciation_019e3c98-dd0a-7973-9606-829185e68770" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_019f5d16-6e8c-73d8-9c35-58bfa5709925" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e3c98-dd0a-71cf-b5bc-cde12d2dd33d" xlink:to="loc_us-gaap_AssetImpairmentCharges_019f5d16-6e8c-73d8-9c35-58bfa5709925" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveAcceleratedDepreciation_019f5d16-6e8c-73f9-9a23-36680d0e9768" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserveAcceleratedDepreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e3c98-dd0a-71cf-b5bc-cde12d2dd33d" xlink:to="loc_us-gaap_RestructuringReserveAcceleratedDepreciation_019f5d16-6e8c-73f9-9a23-36680d0e9768" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/GOODWILLANDINTANGIBLEASSETSANDLIABILITIESGoodwillDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#GOODWILLANDINTANGIBLEASSETSANDLIABILITIESGoodwillDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/GOODWILLANDINTANGIBLEASSETSANDLIABILITIESGoodwillDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_019e3c98-dd0a-7258-a357-369f777a7177" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_019e3c98-dd0a-78b4-87a5-bfc7aba90046" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_019e3c98-dd0a-7258-a357-369f777a7177" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_019e3c98-dd0a-78b4-87a5-bfc7aba90046" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-721f-aa39-1d3b5a551f56" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019e3c98-dd0a-78b4-87a5-bfc7aba90046" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-721f-aa39-1d3b5a551f56" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e3c98-dd0a-721f-aa39-1d3b5a551f56_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-721f-aa39-1d3b5a551f56" xlink:to="loc_us-gaap_SegmentDomain_019e3c98-dd0a-721f-aa39-1d3b5a551f56_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7373-bcdd-3ba839c053da" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e3c98-dd0a-721f-aa39-1d3b5a551f56" xlink:to="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7373-bcdd-3ba839c053da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_SteelmakingMember_019e3c98-dd0a-7039-bde3-7b6d6744afff" xlink:href="clf-20260630.xsd#clf_SteelmakingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7373-bcdd-3ba839c053da" xlink:to="loc_clf_SteelmakingMember_019e3c98-dd0a-7039-bde3-7b6d6744afff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_OtherBusinessesMember_019e3c98-dd0a-78ca-b8b2-ebabd2cc3e4b" xlink:href="clf-20260630.xsd#clf_OtherBusinessesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e3c98-dd0a-7373-bcdd-3ba839c053da" xlink:to="loc_clf_OtherBusinessesMember_019e3c98-dd0a-78ca-b8b2-ebabd2cc3e4b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillRollForward_019e3c98-dd0a-7116-b7c8-1f94016c03c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e3c98-dd0a-7258-a357-369f777a7177" xlink:to="loc_us-gaap_GoodwillRollForward_019e3c98-dd0a-7116-b7c8-1f94016c03c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019e3c98-dd0a-724c-8ff6-d0b5d4b09d27" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019e3c98-dd0a-7116-b7c8-1f94016c03c9" xlink:to="loc_us-gaap_Goodwill_019e3c98-dd0a-724c-8ff6-d0b5d4b09d27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_019e3c98-dd0a-7570-83d7-9ba7d3b33eb5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019e3c98-dd0a-7116-b7c8-1f94016c03c9" xlink:to="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_019e3c98-dd0a-7570-83d7-9ba7d3b33eb5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019e3c98-dd0a-740b-a8f5-c8c4f8893b96" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/GOODWILLANDINTANGIBLEASSETSANDLIABILITIESIntangibleAssetsandLiabilitiesDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#GOODWILLANDINTANGIBLEASSETSANDLIABILITIESIntangibleAssetsandLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/GOODWILLANDINTANGIBLEASSETSANDLIABILITIESIntangibleAssetsandLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019e3c98-dd0a-7e19-b31c-35c9c208d268" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_019e3c98-dd0a-7d1b-8489-b88e7cf6bc0c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019e3c98-dd0a-7e19-b31c-35c9c208d268" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_019e3c98-dd0a-7d1b-8489-b88e7cf6bc0c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e3c98-dd0a-7437-9161-840a40017cf6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_019e3c98-dd0a-7d1b-8489-b88e7cf6bc0c" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e3c98-dd0a-7437-9161-840a40017cf6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e3c98-dd0a-7437-9161-840a40017cf6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e3c98-dd0a-7437-9161-840a40017cf6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e3c98-dd0a-7437-9161-840a40017cf6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e3c98-dd0a-73e9-b541-1c0ad936110b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e3c98-dd0a-7437-9161-840a40017cf6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e3c98-dd0a-73e9-b541-1c0ad936110b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_019e3c98-dd0a-7435-8d30-f7ae532b045e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e3c98-dd0a-73e9-b541-1c0ad936110b" xlink:to="loc_us-gaap_CustomerRelationshipsMember_019e3c98-dd0a-7435-8d30-f7ae532b045e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_019e3c98-dd0a-79e7-9008-509c836f1677" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TechnologyBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e3c98-dd0a-73e9-b541-1c0ad936110b" xlink:to="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_019e3c98-dd0a-79e7-9008-509c836f1677" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksAndTradeNamesMember_019e3c98-dd0a-7bb9-ad1b-a6d6892b5d57" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TrademarksAndTradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e3c98-dd0a-73e9-b541-1c0ad936110b" xlink:to="loc_us-gaap_TrademarksAndTradeNamesMember_019e3c98-dd0a-7bb9-ad1b-a6d6892b5d57" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_MiningPermitsMember_019e3c98-dd0a-72a4-ac37-eb38c288f0b6" xlink:href="clf-20260630.xsd#clf_MiningPermitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e3c98-dd0a-73e9-b541-1c0ad936110b" xlink:to="loc_clf_MiningPermitsMember_019e3c98-dd0a-72a4-ac37-eb38c288f0b6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_SupplierRelationshipsMember_019e3c98-dd0a-7ee2-b4cf-e05c9264a3ae" xlink:href="clf-20260630.xsd#clf_SupplierRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e3c98-dd0a-73e9-b541-1c0ad936110b" xlink:to="loc_clf_SupplierRelationshipsMember_019e3c98-dd0a-7ee2-b4cf-e05c9264a3ae" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_019e3c98-dd0a-72f3-a619-03acd04a6c40" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019e3c98-dd0a-7e19-b31c-35c9c208d268" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_019e3c98-dd0a-72f3-a619-03acd04a6c40" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019e3c98-dd0a-7f7c-b3e8-52b44813b677" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019e3c98-dd0a-7e19-b31c-35c9c208d268" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019e3c98-dd0a-7f7c-b3e8-52b44813b677" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_019e3c98-dd0a-7e44-b38f-ac7a20c0204f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019e3c98-dd0a-7e19-b31c-35c9c208d268" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_019e3c98-dd0a-7e44-b38f-ac7a20c0204f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_FiniteLivedIntangibleLiabilityGross_019e3c98-dd0a-72ee-84fb-b9c56c478b1e" xlink:href="clf-20260630.xsd#clf_FiniteLivedIntangibleLiabilityGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019e3c98-dd0a-7e19-b31c-35c9c208d268" xlink:to="loc_clf_FiniteLivedIntangibleLiabilityGross_019e3c98-dd0a-72ee-84fb-b9c56c478b1e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_FiniteLivedIntangibleLiabilityAccumulatedAmortization_019e3c98-dd0a-747f-b9d2-dbdac0ccef47" xlink:href="clf-20260630.xsd#clf_FiniteLivedIntangibleLiabilityAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019e3c98-dd0a-7e19-b31c-35c9c208d268" xlink:to="loc_clf_FiniteLivedIntangibleLiabilityAccumulatedAmortization_019e3c98-dd0a-747f-b9d2-dbdac0ccef47" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_FiniteLivedIntangibleLiabilityNet_019e3c98-dd0a-7f0b-8cf1-0e8646675b08" xlink:href="clf-20260630.xsd#clf_FiniteLivedIntangibleLiabilityNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019e3c98-dd0a-7e19-b31c-35c9c208d268" xlink:to="loc_clf_FiniteLivedIntangibleLiabilityNet_019e3c98-dd0a-7f0b-8cf1-0e8646675b08" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/DEBTANDCREDITFACILITIESScheduleOfLongTermDebtDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#DEBTANDCREDITFACILITIESScheduleOfLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/DEBTANDCREDITFACILITIESScheduleOfLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e3c98-dd0a-785a-b6fe-f2e677212b7f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019e3c98-dd0a-7de2-9e0d-d6c191d49786" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e3c98-dd0a-785a-b6fe-f2e677212b7f" xlink:to="loc_us-gaap_DebtInstrumentTable_019e3c98-dd0a-7de2-9e0d-d6c191d49786" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e3c98-dd0a-70ef-a67a-d8236d447619" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e3c98-dd0a-7de2-9e0d-d6c191d49786" xlink:to="loc_dei_LegalEntityAxis_019e3c98-dd0a-70ef-a67a-d8236d447619" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e3c98-dd0a-70ef-a67a-d8236d447619_default" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e3c98-dd0a-70ef-a67a-d8236d447619" xlink:to="loc_dei_EntityDomain_019e3c98-dd0a-70ef-a67a-d8236d447619_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e3c98-dd0a-7915-81de-a4c6a85f231a" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e3c98-dd0a-70ef-a67a-d8236d447619" xlink:to="loc_dei_EntityDomain_019e3c98-dd0a-7915-81de-a4c6a85f231a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_ClevelandCliffsInc.Member_019e3c98-dd0a-72c3-a417-358019b1f26d" xlink:href="clf-20260630.xsd#clf_ClevelandCliffsInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e3c98-dd0a-7915-81de-a4c6a85f231a" xlink:to="loc_clf_ClevelandCliffsInc.Member_019e3c98-dd0a-72c3-a417-358019b1f26d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e3c98-dd0a-7ae2-a647-cb9b0d555380" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e3c98-dd0a-7de2-9e0d-d6c191d49786" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e3c98-dd0a-7ae2-a647-cb9b0d555380" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-7ae2-a647-cb9b0d555380_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e3c98-dd0a-7ae2-a647-cb9b0d555380" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-7ae2-a647-cb9b0d555380_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-762a-a928-24958119f52e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e3c98-dd0a-7ae2-a647-cb9b0d555380" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-762a-a928-24958119f52e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_A46252029SeniorNotesMember_019e3c98-dd0a-7ec3-b3b7-99fe15e58d53" xlink:href="clf-20260630.xsd#clf_A46252029SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-762a-a928-24958119f52e" xlink:to="loc_clf_A46252029SeniorNotesMember_019e3c98-dd0a-7ec3-b3b7-99fe15e58d53" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_A6.8752029SeniorNotesMember_019e3c98-dd0a-7023-b77c-bd9ade29174c" xlink:href="clf-20260630.xsd#clf_A6.8752029SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-762a-a928-24958119f52e" xlink:to="loc_clf_A6.8752029SeniorNotesMember_019e3c98-dd0a-7023-b77c-bd9ade29174c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_A67502030SeniorNotesMember_019e3c98-dd0a-7700-8bfc-804c41cea614" xlink:href="clf-20260630.xsd#clf_A67502030SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-762a-a928-24958119f52e" xlink:to="loc_clf_A67502030SeniorNotesMember_019e3c98-dd0a-7700-8bfc-804c41cea614" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_A48752031SeniorNotesMember_019e3c98-dd0a-7c03-9d4b-ee98beaa87fc" xlink:href="clf-20260630.xsd#clf_A48752031SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-762a-a928-24958119f52e" xlink:to="loc_clf_A48752031SeniorNotesMember_019e3c98-dd0a-7c03-9d4b-ee98beaa87fc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_A7.5002031SeniorNotesMember_019e3c98-dd0a-7101-a7a9-5928f5ace26a" xlink:href="clf-20260630.xsd#clf_A7.5002031SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-762a-a928-24958119f52e" xlink:to="loc_clf_A7.5002031SeniorNotesMember_019e3c98-dd0a-7101-a7a9-5928f5ace26a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_A7.0002032SeniorNotesMember_019e3c98-dd0a-7b52-ab98-73c778cc1863" xlink:href="clf-20260630.xsd#clf_A7.0002032SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-762a-a928-24958119f52e" xlink:to="loc_clf_A7.0002032SeniorNotesMember_019e3c98-dd0a-7b52-ab98-73c778cc1863" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_A7.3752033SeniorNotesMember_019e3c98-dd0a-7697-9b31-7d3ea0c8e183" xlink:href="clf-20260630.xsd#clf_A7.3752033SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-762a-a928-24958119f52e" xlink:to="loc_clf_A7.3752033SeniorNotesMember_019e3c98-dd0a-7697-9b31-7d3ea0c8e183" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_A7.6252034SeniorNotesMember_019e3c98-dd0a-7682-93f6-f134b4d54064" xlink:href="clf-20260630.xsd#clf_A7.6252034SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-762a-a928-24958119f52e" xlink:to="loc_clf_A7.6252034SeniorNotesMember_019e3c98-dd0a-7682-93f6-f134b4d54064" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_A62502040SeniorNotesMember_019e3c98-dd0a-769c-aebc-80bae71108b6" xlink:href="clf-20260630.xsd#clf_A62502040SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-762a-a928-24958119f52e" xlink:to="loc_clf_A62502040SeniorNotesMember_019e3c98-dd0a-769c-aebc-80bae71108b6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019e3c98-dd0a-71c8-9c61-1ebb5a5f9d0d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-762a-a928-24958119f52e" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019e3c98-dd0a-71c8-9c61-1ebb5a5f9d0d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e3c98-dd0a-7c09-a49d-c87d30d1ac53" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e3c98-dd0a-7de2-9e0d-d6c191d49786" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e3c98-dd0a-7c09-a49d-c87d30d1ac53" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e3c98-dd0a-7c09-a49d-c87d30d1ac53_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e3c98-dd0a-7c09-a49d-c87d30d1ac53" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e3c98-dd0a-7c09-a49d-c87d30d1ac53_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e3c98-dd0a-770b-9cd4-39d8792cb7ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e3c98-dd0a-7c09-a49d-c87d30d1ac53" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e3c98-dd0a-770b-9cd4-39d8792cb7ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019e3c98-dd0a-7744-add6-589cf91b4ddb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e3c98-dd0a-770b-9cd4-39d8792cb7ae" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019e3c98-dd0a-7744-add6-589cf91b4ddb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019e3c98-dd0a-7f58-b6c7-f898287660bd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e3c98-dd0a-785a-b6fe-f2e677212b7f" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019e3c98-dd0a-7f58-b6c7-f898287660bd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019e3c98-dd0a-7900-8ba4-40c5e8df8366" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e3c98-dd0a-785a-b6fe-f2e677212b7f" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019e3c98-dd0a-7900-8ba4-40c5e8df8366" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019e3c98-dd0a-78d4-bd0c-56fe7261a8e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e3c98-dd0a-785a-b6fe-f2e677212b7f" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019e3c98-dd0a-78d4-bd0c-56fe7261a8e0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_019e3c98-dd0a-75cc-a32d-0429de406443" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e3c98-dd0a-785a-b6fe-f2e677212b7f" xlink:to="loc_us-gaap_LineOfCredit_019e3c98-dd0a-75cc-a32d-0429de406443" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_019e3c98-dd0a-7945-9477-176375683330" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e3c98-dd0a-785a-b6fe-f2e677212b7f" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_019e3c98-dd0a-7945-9477-176375683330" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019e3c98-dd0a-739e-92be-ee6c61a4b7d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e3c98-dd0a-785a-b6fe-f2e677212b7f" xlink:to="loc_us-gaap_LongTermDebt_019e3c98-dd0a-739e-92be-ee6c61a4b7d0" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/DEBTANDCREDITFACILITIESABLFacilityDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#DEBTANDCREDITFACILITIESABLFacilityDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/DEBTANDCREDITFACILITIESABLFacilityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_019e3c98-dd0a-705d-bf2a-7770b6126644" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_019e3c98-dd0a-7bfc-8de2-ce196af3631d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e3c98-dd0a-705d-bf2a-7770b6126644" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_019e3c98-dd0a-7bfc-8de2-ce196af3631d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e3c98-dd0a-7fd3-91b6-c01b37e1b4cb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_019e3c98-dd0a-7bfc-8de2-ce196af3631d" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e3c98-dd0a-7fd3-91b6-c01b37e1b4cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-7fd3-91b6-c01b37e1b4cb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e3c98-dd0a-7fd3-91b6-c01b37e1b4cb" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-7fd3-91b6-c01b37e1b4cb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-7e25-bab6-cc3d995c8f2a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e3c98-dd0a-7fd3-91b6-c01b37e1b4cb" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-7e25-bab6-cc3d995c8f2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019e3c98-dd0a-7c35-8bf3-4c66e49ac75f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-7e25-bab6-cc3d995c8f2a" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019e3c98-dd0a-7c35-8bf3-4c66e49ac75f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_019e3c98-dd0a-71c9-8b75-90a7203cddce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0a-7e25-bab6-cc3d995c8f2a" xlink:to="loc_us-gaap_LetterOfCreditMember_019e3c98-dd0a-71c9-8b75-90a7203cddce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e3c98-dd0a-7da0-a148-60a9dae3ea4e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_019e3c98-dd0a-7bfc-8de2-ce196af3631d" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e3c98-dd0a-7da0-a148-60a9dae3ea4e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e3c98-dd0a-7da0-a148-60a9dae3ea4e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e3c98-dd0a-7da0-a148-60a9dae3ea4e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e3c98-dd0a-7da0-a148-60a9dae3ea4e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e3c98-dd0a-7ad5-870b-ea33fc19f4f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e3c98-dd0a-7da0-a148-60a9dae3ea4e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e3c98-dd0a-7ad5-870b-ea33fc19f4f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019e3c98-dd0a-7323-9a5c-d5b7c5230859" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e3c98-dd0a-7ad5-870b-ea33fc19f4f4" xlink:to="loc_us-gaap_LineOfCreditMember_019e3c98-dd0a-7323-9a5c-d5b7c5230859" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_DebtInstrumentCovenantFixedChargeCoverageRatioMinimum_019e3c98-dd0a-7b77-ae41-2548df7a5b67" xlink:href="clf-20260630.xsd#clf_DebtInstrumentCovenantFixedChargeCoverageRatioMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e3c98-dd0a-705d-bf2a-7770b6126644" xlink:to="loc_clf_DebtInstrumentCovenantFixedChargeCoverageRatioMinimum_019e3c98-dd0a-7b77-ae41-2548df7a5b67" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_019e3c98-dd0a-7c9b-b898-ac81671e014b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e3c98-dd0a-705d-bf2a-7770b6126644" xlink:to="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_019e3c98-dd0a-7c9b-b898-ac81671e014b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_019e3c98-dd0a-7db5-8057-7689b1cb5182" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e3c98-dd0a-705d-bf2a-7770b6126644" xlink:to="loc_us-gaap_LineOfCredit_019e3c98-dd0a-7db5-8057-7689b1cb5182" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019e3c98-dd0a-7938-90a9-e5dcd8b03d13" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e3c98-dd0a-705d-bf2a-7770b6126644" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019e3c98-dd0a-7938-90a9-e5dcd8b03d13" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019e3c98-dd0a-7a5f-9768-b84cc602a9dc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e3c98-dd0a-705d-bf2a-7770b6126644" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019e3c98-dd0a-7a5f-9768-b84cc602a9dc" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/PENSIONSANDOTHERPOSTRETIREMENTBENEFITSPensionandOtherPostretirementBenefitsDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#PENSIONSANDOTHERPOSTRETIREMENTBENEFITSPensionandOtherPostretirementBenefitsDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/PENSIONSANDOTHERPOSTRETIREMENTBENEFITSPensionandOtherPostretirementBenefitsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e3c98-dd0a-7f31-82d3-54cf08d8b807" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_019e3c98-dd0a-7152-881d-8ecb459b80fd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e3c98-dd0a-7f31-82d3-54cf08d8b807" xlink:to="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_019e3c98-dd0a-7152-881d-8ecb459b80fd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_019e3c98-dd0a-7c3e-8a12-0f8dfe563f84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_019e3c98-dd0a-7152-881d-8ecb459b80fd" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_019e3c98-dd0a-7c3e-8a12-0f8dfe563f84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_019e3c98-dd0a-7c3e-8a12-0f8dfe563f84_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_019e3c98-dd0a-7c3e-8a12-0f8dfe563f84" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_019e3c98-dd0a-7c3e-8a12-0f8dfe563f84_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_019e3c98-dd0a-78fa-9440-2b66128cfc3f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_019e3c98-dd0a-7c3e-8a12-0f8dfe563f84" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_019e3c98-dd0a-78fa-9440-2b66128cfc3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_019e3c98-dd0a-77ff-b025-b3f52b7c4c47" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_019e3c98-dd0a-78fa-9440-2b66128cfc3f" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_019e3c98-dd0a-77ff-b025-b3f52b7c4c47" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_019e3c98-dd0a-74f7-aeff-3edd2eb445a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_019e3c98-dd0a-78fa-9440-2b66128cfc3f" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_019e3c98-dd0a-74f7-aeff-3edd2eb445a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_019e3c98-dd0a-7e69-a7ae-d66487f441f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e3c98-dd0a-7f31-82d3-54cf08d8b807" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_019e3c98-dd0a-7e69-a7ae-d66487f441f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_019e3c98-dd0a-703c-8262-f3d7ce2d7de3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e3c98-dd0a-7f31-82d3-54cf08d8b807" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_019e3c98-dd0a-703c-8262-f3d7ce2d7de3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_019e3c98-dd0a-7b04-9235-8a191bb10c19" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e3c98-dd0a-7f31-82d3-54cf08d8b807" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_019e3c98-dd0a-7b04-9235-8a191bb10c19" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanOtherCosts_019edb40-4d4f-7eb7-acc0-94e6a0552cb1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanOtherCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e3c98-dd0a-7f31-82d3-54cf08d8b807" xlink:to="loc_us-gaap_DefinedBenefitPlanOtherCosts_019edb40-4d4f-7eb7-acc0-94e6a0552cb1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_019e3c98-dd0a-7fba-aa27-9a3807c90cb0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e3c98-dd0a-7f31-82d3-54cf08d8b807" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_019e3c98-dd0a-7fba-aa27-9a3807c90cb0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_019e3c98-dd0a-7331-86f7-6b2edb401731" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e3c98-dd0a-7f31-82d3-54cf08d8b807" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_019e3c98-dd0a-7331-86f7-6b2edb401731" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_019e3c98-dd0a-7554-9b66-2e38abab2676" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e3c98-dd0a-7f31-82d3-54cf08d8b807" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_019e3c98-dd0a-7554-9b66-2e38abab2676" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionContributions_019e3c98-dd0b-71b7-b22c-7fa5d007d6e7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionContributions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e3c98-dd0a-7f31-82d3-54cf08d8b807" xlink:to="loc_us-gaap_PensionContributions_019e3c98-dd0b-71b7-b22c-7fa5d007d6e7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitsPayments_019e3c98-dd0b-77cf-b283-767a36f85121" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherPostretirementBenefitsPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e3c98-dd0a-7f31-82d3-54cf08d8b807" xlink:to="loc_us-gaap_OtherPostretirementBenefitsPayments_019e3c98-dd0b-77cf-b283-767a36f85121" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/STOCKCOMPENSATIONPLANSDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#STOCKCOMPENSATIONPLANSDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/STOCKCOMPENSATIONPLANSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e3c98-dd0b-7f5e-bdc8-82be1bd43ec6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e3c98-dd0b-7169-9c06-d9313d4fe912" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e3c98-dd0b-7f5e-bdc8-82be1bd43ec6" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e3c98-dd0b-7169-9c06-d9313d4fe912" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e3c98-dd0b-7879-a793-fde7ba3de8f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e3c98-dd0b-7169-9c06-d9313d4fe912" xlink:to="loc_us-gaap_AwardTypeAxis_019e3c98-dd0b-7879-a793-fde7ba3de8f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e3c98-dd0b-7879-a793-fde7ba3de8f9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e3c98-dd0b-7879-a793-fde7ba3de8f9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e3c98-dd0b-7879-a793-fde7ba3de8f9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e3c98-dd0b-717a-900e-64cb5b33bc0f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e3c98-dd0b-7879-a793-fde7ba3de8f9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e3c98-dd0b-717a-900e-64cb5b33bc0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_MarketStockUnitsMember_019e3c98-dd0b-7149-bc97-26e68c587110" xlink:href="clf-20260630.xsd#clf_MarketStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e3c98-dd0b-717a-900e-64cb5b33bc0f" xlink:to="loc_clf_MarketStockUnitsMember_019e3c98-dd0b-7149-bc97-26e68c587110" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e3c98-dd0b-7f1a-944b-7b8729be5b7f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e3c98-dd0b-7169-9c06-d9313d4fe912" xlink:to="loc_srt_RangeAxis_019e3c98-dd0b-7f1a-944b-7b8729be5b7f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e3c98-dd0b-7f1a-944b-7b8729be5b7f_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e3c98-dd0b-7f1a-944b-7b8729be5b7f" xlink:to="loc_srt_RangeMember_019e3c98-dd0b-7f1a-944b-7b8729be5b7f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e3c98-dd0b-7eea-b970-5bdcc563eb06" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e3c98-dd0b-7f1a-944b-7b8729be5b7f" xlink:to="loc_srt_RangeMember_019e3c98-dd0b-7eea-b970-5bdcc563eb06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e3c98-dd0b-751b-8014-bcd28939ff76" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e3c98-dd0b-7eea-b970-5bdcc563eb06" xlink:to="loc_srt_MinimumMember_019e3c98-dd0b-751b-8014-bcd28939ff76" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e3c98-dd0b-7c02-b1c0-8f33b751d441" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e3c98-dd0b-7eea-b970-5bdcc563eb06" xlink:to="loc_srt_MaximumMember_019e3c98-dd0b-7c02-b1c0-8f33b751d441" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019e3c98-dd0b-7b0b-aefd-744e2fa94d9e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e3c98-dd0b-7f5e-bdc8-82be1bd43ec6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019e3c98-dd0b-7b0b-aefd-744e2fa94d9e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformancePeriod_019e3c98-dd0b-7ccd-8af7-253314edf5f4" xlink:href="clf-20260630.xsd#clf_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformancePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e3c98-dd0b-7f5e-bdc8-82be1bd43ec6" xlink:to="loc_clf_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformancePeriod_019e3c98-dd0b-7ccd-8af7-253314edf5f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateIntrinsicValue_019e3c98-dd0b-7555-8332-9be5f5e29ab0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e3c98-dd0b-7f5e-bdc8-82be1bd43ec6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateIntrinsicValue_019e3c98-dd0b-7555-8332-9be5f5e29ab0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_019e3c98-dd0b-760d-87f6-a49141622732" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e3c98-dd0b-7f5e-bdc8-82be1bd43ec6" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_019e3c98-dd0b-760d-87f6-a49141622732" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019e3c98-dd0b-7ae5-8669-c38a13b6ffe2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e3c98-dd0b-7f5e-bdc8-82be1bd43ec6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019e3c98-dd0b-7ae5-8669-c38a13b6ffe2" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/ASSETRETIREMENTOBLIGATIONSSummaryOfAssetRetirementObligationsDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#ASSETRETIREMENTOBLIGATIONSSummaryOfAssetRetirementObligationsDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/ASSETRETIREMENTOBLIGATIONSSummaryOfAssetRetirementObligationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalExitCostLineItems_019e3c98-dd0b-7cec-aebe-71383e458bf4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EnvironmentalExitCostLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEnvironmentalExitCostTable_019e3c98-dd0b-7a88-82e8-116727d506d8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEnvironmentalExitCostTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EnvironmentalExitCostLineItems_019e3c98-dd0b-7cec-aebe-71383e458bf4" xlink:to="loc_us-gaap_ScheduleOfEnvironmentalExitCostTable_019e3c98-dd0b-7a88-82e8-116727d506d8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019e3c98-dd0b-7817-9fad-4a6d2fe5099f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEnvironmentalExitCostTable_019e3c98-dd0b-7a88-82e8-116727d506d8" xlink:to="loc_srt_ConsolidationItemsAxis_019e3c98-dd0b-7817-9fad-4a6d2fe5099f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e3c98-dd0b-7817-9fad-4a6d2fe5099f_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019e3c98-dd0b-7817-9fad-4a6d2fe5099f" xlink:to="loc_srt_ConsolidationItemsDomain_019e3c98-dd0b-7817-9fad-4a6d2fe5099f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e3c98-dd0b-7a70-a161-8a003b43440f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019e3c98-dd0b-7817-9fad-4a6d2fe5099f" xlink:to="loc_srt_ConsolidationItemsDomain_019e3c98-dd0b-7a70-a161-8a003b43440f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019e3c98-dd0b-743f-8a18-f3f7e49e2240" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019e3c98-dd0b-7a70-a161-8a003b43440f" xlink:to="loc_us-gaap_OperatingSegmentsMember_019e3c98-dd0b-743f-8a18-f3f7e49e2240" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligation_019e3c98-dd0b-7306-a040-e36cdeb99906" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetRetirementObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EnvironmentalExitCostLineItems_019e3c98-dd0b-7cec-aebe-71383e458bf4" xlink:to="loc_us-gaap_AssetRetirementObligation_019e3c98-dd0b-7306-a040-e36cdeb99906" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationCurrent_019e3c98-dd0b-7cab-a49d-d6b5bcf09c15" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetRetirementObligationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EnvironmentalExitCostLineItems_019e3c98-dd0b-7cec-aebe-71383e458bf4" xlink:to="loc_us-gaap_AssetRetirementObligationCurrent_019e3c98-dd0b-7cab-a49d-d6b5bcf09c15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationsNoncurrent_019e3c98-dd0b-73be-bf38-31d49a9a17e6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetRetirementObligationsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EnvironmentalExitCostLineItems_019e3c98-dd0b-7cec-aebe-71383e458bf4" xlink:to="loc_us-gaap_AssetRetirementObligationsNoncurrent_019e3c98-dd0b-73be-bf38-31d49a9a17e6" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/FAIRVALUEMEASUREMENTSCarryingValueAndFairValueOfFinancialInstrumentsDisclosureDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#FAIRVALUEMEASUREMENTSCarryingValueAndFairValueOfFinancialInstrumentsDisclosureDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/FAIRVALUEMEASUREMENTSCarryingValueAndFairValueOfFinancialInstrumentsDisclosureDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e3c98-dd0b-7760-ac88-737ba377bfef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e3c98-dd0b-7c90-8cb9-5477911c8d27" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByBalanceSheetGroupingTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e3c98-dd0b-7760-ac88-737ba377bfef" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e3c98-dd0b-7c90-8cb9-5477911c8d27" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e3c98-dd0b-70f4-a70d-631b18d432a1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e3c98-dd0b-7c90-8cb9-5477911c8d27" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e3c98-dd0b-70f4-a70d-631b18d432a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e3c98-dd0b-70f4-a70d-631b18d432a1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e3c98-dd0b-70f4-a70d-631b18d432a1" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e3c98-dd0b-70f4-a70d-631b18d432a1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e3c98-dd0b-709d-9cf7-52129c6a03cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e3c98-dd0b-70f4-a70d-631b18d432a1" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e3c98-dd0b-709d-9cf7-52129c6a03cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019e3c98-dd0b-7852-a977-9c7d1508ca07" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e3c98-dd0b-709d-9cf7-52129c6a03cd" xlink:to="loc_us-gaap_SeniorNotesMember_019e3c98-dd0b-7852-a977-9c7d1508ca07" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019e3c98-dd0b-74d0-bf41-6e178cd45ff4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e3c98-dd0b-709d-9cf7-52129c6a03cd" xlink:to="loc_us-gaap_LineOfCreditMember_019e3c98-dd0b-74d0-bf41-6e178cd45ff4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e3c98-dd0b-7165-b8d6-468bbdfa4f1b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e3c98-dd0b-7c90-8cb9-5477911c8d27" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e3c98-dd0b-7165-b8d6-468bbdfa4f1b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e3c98-dd0b-7165-b8d6-468bbdfa4f1b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e3c98-dd0b-7165-b8d6-468bbdfa4f1b" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e3c98-dd0b-7165-b8d6-468bbdfa4f1b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e3c98-dd0b-7c93-9f9e-9b2f8f2122b8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e3c98-dd0b-7165-b8d6-468bbdfa4f1b" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e3c98-dd0b-7c93-9f9e-9b2f8f2122b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019e3c98-dd0b-73f8-8cf0-d20430a72377" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e3c98-dd0b-7c93-9f9e-9b2f8f2122b8" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019e3c98-dd0b-73f8-8cf0-d20430a72377" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019e3c98-dd0b-7dfd-8773-cad762ee612f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e3c98-dd0b-7c93-9f9e-9b2f8f2122b8" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019e3c98-dd0b-7dfd-8773-cad762ee612f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e3c98-dd0b-7585-90e7-d303c4cbda3a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e3c98-dd0b-7c90-8cb9-5477911c8d27" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e3c98-dd0b-7585-90e7-d303c4cbda3a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0b-7585-90e7-d303c4cbda3a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e3c98-dd0b-7585-90e7-d303c4cbda3a" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0b-7585-90e7-d303c4cbda3a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0b-7593-accb-5ffe526b9f50" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e3c98-dd0b-7585-90e7-d303c4cbda3a" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0b-7593-accb-5ffe526b9f50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019e3c98-dd0b-7c98-9a55-9a6982e84ad4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dd0b-7593-accb-5ffe526b9f50" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019e3c98-dd0b-7c98-9a55-9a6982e84ad4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_019e3c98-dd0b-725f-92f8-ffbd321032f6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019e3c98-dd0b-7c90-8cb9-5477911c8d27" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_019e3c98-dd0b-725f-92f8-ffbd321032f6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e3c98-dd0b-725f-92f8-ffbd321032f6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_019e3c98-dd0b-725f-92f8-ffbd321032f6" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e3c98-dd0b-725f-92f8-ffbd321032f6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019e3c98-dd0b-709a-a934-f53f7434f6ac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_019e3c98-dd0b-725f-92f8-ffbd321032f6" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019e3c98-dd0b-709a-a934-f53f7434f6ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e3c98-dd0b-7784-8d84-bddac516863f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019e3c98-dd0b-709a-a934-f53f7434f6ac" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e3c98-dd0b-7784-8d84-bddac516863f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019e3c98-dd0b-7ecf-8eb3-42f42aeff870" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e3c98-dd0b-7784-8d84-bddac516863f" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019e3c98-dd0b-7ecf-8eb3-42f42aeff870" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019e3c98-dd0b-7f04-919b-8abbfa8daa9b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019e3c98-dd0b-7784-8d84-bddac516863f" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019e3c98-dd0b-7f04-919b-8abbfa8daa9b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_019e3c98-dd0b-71eb-9f3a-ad6c93985d4a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019e3c98-dd0b-7760-ac88-737ba377bfef" xlink:to="loc_us-gaap_LongTermDebtFairValue_019e3c98-dd0b-71eb-9f3a-ad6c93985d4a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/FAIRVALUEMEASUREMENTSEmployeeBenefitCommitmentDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#FAIRVALUEMEASUREMENTSEmployeeBenefitCommitmentDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/FAIRVALUEMEASUREMENTSEmployeeBenefitCommitmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e3c98-dd0b-7674-b9aa-635f829a8114" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e3c98-dd0b-7e33-870b-81c757ebf886" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e3c98-dd0b-7674-b9aa-635f829a8114" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e3c98-dd0b-7e33-870b-81c757ebf886" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_019e3c98-dd0b-73e3-af68-22ecfbe05d41" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByLiabilityClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e3c98-dd0b-7e33-870b-81c757ebf886" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_019e3c98-dd0b-73e3-af68-22ecfbe05d41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_019e3c98-dd0b-73e3-af68-22ecfbe05d41_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_019e3c98-dd0b-73e3-af68-22ecfbe05d41" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_019e3c98-dd0b-73e3-af68-22ecfbe05d41_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_019e3c98-dd0b-7e42-a879-fd20ab50d0c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_019e3c98-dd0b-73e3-af68-22ecfbe05d41" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_019e3c98-dd0b-7e42-a879-fd20ab50d0c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsMember_019e3c98-dd0b-78df-bf04-815cc75afd4a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommitmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_019e3c98-dd0b-7e42-a879-fd20ab50d0c8" xlink:to="loc_us-gaap_CommitmentsMember_019e3c98-dd0b-78df-bf04-815cc75afd4a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_019e3c98-dd0b-77c0-9601-2bb443842bf4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e3c98-dd0b-7674-b9aa-635f829a8114" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_019e3c98-dd0b-77c0-9601-2bb443842bf4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings_019e3c98-dd0b-766d-ac6b-35e9a5cef7f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e3c98-dd0b-7674-b9aa-635f829a8114" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings_019e3c98-dd0b-766d-ac6b-35e9a5cef7f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases_019e3c98-dd0b-725d-b06b-f1bb9b53997a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e3c98-dd0b-7674-b9aa-635f829a8114" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases_019e3c98-dd0b-725d-b06b-f1bb9b53997a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityForeignCurrencyTranslation_019e3c98-dd0b-7334-9d3b-1e6aab45e99d" xlink:href="clf-20260630.xsd#clf_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityForeignCurrencyTranslation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e3c98-dd0b-7674-b9aa-635f829a8114" xlink:to="loc_clf_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityForeignCurrencyTranslation_019e3c98-dd0b-7334-9d3b-1e6aab45e99d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_019e3c98-dd0b-7923-9c19-f250be3bc505" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/FAIRVALUEMEASUREMENTSMinnTacOptionDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#FAIRVALUEMEASUREMENTSMinnTacOptionDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/FAIRVALUEMEASUREMENTSMinnTacOptionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e3c98-dd0b-7dff-b05e-4d706e477f26" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e3c98-dd0b-768f-bc8b-068db25b94ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e3c98-dd0b-7dff-b05e-4d706e477f26" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e3c98-dd0b-768f-bc8b-068db25b94ba" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e3c98-dd0b-7a93-82d8-b285510afa48" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e3c98-dd0b-768f-bc8b-068db25b94ba" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e3c98-dd0b-7a93-82d8-b285510afa48" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e3c98-dd0b-7a93-82d8-b285510afa48_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e3c98-dd0b-7a93-82d8-b285510afa48" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e3c98-dd0b-7a93-82d8-b285510afa48_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e3c98-dd0b-7a38-be1a-a77862814695" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e3c98-dd0b-7a93-82d8-b285510afa48" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e3c98-dd0b-7a38-be1a-a77862814695" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityOptionMember_019e3c98-dd0b-78fa-ba42-a1fdbe41326f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommodityOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e3c98-dd0b-7a38-be1a-a77862814695" xlink:to="loc_us-gaap_CommodityOptionMember_019e3c98-dd0b-78fa-ba42-a1fdbe41326f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_DerivativeInstrumentPercentageOfInterestInCommodityOption_019e3c98-dd0b-7c00-adc7-bdbd6ad3bec9" xlink:href="clf-20260630.xsd#clf_DerivativeInstrumentPercentageOfInterestInCommodityOption"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e3c98-dd0b-7dff-b05e-4d706e477f26" xlink:to="loc_clf_DerivativeInstrumentPercentageOfInterestInCommodityOption_019e3c98-dd0b-7c00-adc7-bdbd6ad3bec9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019e3c98-dd0b-7edf-aab0-cc5ad7f7fb4d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e3c98-dd0b-7dff-b05e-4d706e477f26" xlink:to="loc_us-gaap_DerivativeAssets_019e3c98-dd0b-7edf-aab0-cc5ad7f7fb4d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_019e3c98-dd0b-7883-a659-a691a8a4ba6c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e3c98-dd0b-7dff-b05e-4d706e477f26" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_019e3c98-dd0b-7883-a659-a691a8a4ba6c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings_019e3c98-dd0b-776c-bfdb-a89ba0d1aedf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e3c98-dd0b-7dff-b05e-4d706e477f26" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings_019e3c98-dd0b-776c-bfdb-a89ba0d1aedf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationForeignCurrencyTranslation_019e3c98-dd0b-70ea-a270-0170b46ab924" xlink:href="clf-20260630.xsd#clf_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationForeignCurrencyTranslation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e3c98-dd0b-7dff-b05e-4d706e477f26" xlink:to="loc_clf_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationForeignCurrencyTranslation_019e3c98-dd0b-70ea-a270-0170b46ab924" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_019e3c98-dd0b-75d0-9f38-71feaf5ae4c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#DERIVATIVEINSTRUMENTSANDHEDGINGDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e3c98-dd0b-7795-a044-3db8818dfacc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e3c98-dd0b-79aa-b224-8f118365175b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e3c98-dd0b-7795-a044-3db8818dfacc" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e3c98-dd0b-79aa-b224-8f118365175b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e3c98-dd0b-70a8-94bb-e8d10773bd86" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e3c98-dd0b-79aa-b224-8f118365175b" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e3c98-dd0b-70a8-94bb-e8d10773bd86" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e3c98-dd0b-70a8-94bb-e8d10773bd86_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e3c98-dd0b-70a8-94bb-e8d10773bd86" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e3c98-dd0b-70a8-94bb-e8d10773bd86_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e3c98-dd0b-7703-b8d7-55672b57e818" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e3c98-dd0b-70a8-94bb-e8d10773bd86" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e3c98-dd0b-7703-b8d7-55672b57e818" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019e3c98-dd0b-72cd-bee5-7844e3d50c9f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e3c98-dd0b-7703-b8d7-55672b57e818" xlink:to="loc_us-gaap_CommodityContractMember_019e3c98-dd0b-72cd-bee5-7844e3d50c9f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_CashSettledSalesSwapsMember_019e3c98-dd0b-79b8-b057-b947e6b21005" xlink:href="clf-20260630.xsd#clf_CashSettledSalesSwapsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e3c98-dd0b-7703-b8d7-55672b57e818" xlink:to="loc_clf_CashSettledSalesSwapsMember_019e3c98-dd0b-79b8-b057-b947e6b21005" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyAxis_019e3c98-dd0b-79da-8d3f-ad348d4620f1" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EnergyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e3c98-dd0b-79aa-b224-8f118365175b" xlink:to="loc_srt_EnergyAxis_019e3c98-dd0b-79da-8d3f-ad348d4620f1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyDomain_019e3c98-dd0b-79da-8d3f-ad348d4620f1_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_EnergyAxis_019e3c98-dd0b-79da-8d3f-ad348d4620f1" xlink:to="loc_srt_EnergyDomain_019e3c98-dd0b-79da-8d3f-ad348d4620f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyDomain_019e3c98-dd0b-7e38-baca-e8f39510cc66" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_EnergyAxis_019e3c98-dd0b-79da-8d3f-ad348d4620f1" xlink:to="loc_srt_EnergyDomain_019e3c98-dd0b-7e38-baca-e8f39510cc66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NaturalGasPerThousandCubicFeetMember_019e3c98-dd0b-7d89-8c33-b32168ad060f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NaturalGasPerThousandCubicFeetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_019e3c98-dd0b-7e38-baca-e8f39510cc66" xlink:to="loc_srt_NaturalGasPerThousandCubicFeetMember_019e3c98-dd0b-7d89-8c33-b32168ad060f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ElectricityMember_019e3c98-dd0b-7ac7-9292-c12fc5e1c82d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ElectricityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_019e3c98-dd0b-7e38-baca-e8f39510cc66" xlink:to="loc_us-gaap_ElectricityMember_019e3c98-dd0b-7ac7-9292-c12fc5e1c82d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_HRCMember_019e3c98-dd0b-7356-abd3-d5b727ac3fa8" xlink:href="clf-20260630.xsd#clf_HRCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_019e3c98-dd0b-7e38-baca-e8f39510cc66" xlink:to="loc_clf_HRCMember_019e3c98-dd0b-7356-abd3-d5b727ac3fa8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmount_019e3c98-dd0b-7956-a44b-0cfc3f0dae2f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeNonmonetaryNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e3c98-dd0b-7795-a044-3db8818dfacc" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmount_019e3c98-dd0b-7956-a44b-0cfc3f0dae2f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred_019e3c98-dd0b-7c0d-82b6-af60511fdde2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e3c98-dd0b-7795-a044-3db8818dfacc" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred_019e3c98-dd0b-7c0d-82b6-af60511fdde2" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/CAPITALSTOCKNarrativeDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#CAPITALSTOCKNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/CAPITALSTOCKNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_019e3c98-dd0b-7a6f-97d8-1c7622c2193f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_019e3c98-dd0b-78c7-b997-623f2d18e69e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e3c98-dd0b-7a6f-97d8-1c7622c2193f" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_019e3c98-dd0b-78c7-b997-623f2d18e69e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_019e3c98-dd0b-7255-a419-20ab9a4b8d20" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_019e3c98-dd0b-78c7-b997-623f2d18e69e" xlink:to="loc_us-gaap_StatementClassOfStockAxis_019e3c98-dd0b-7255-a419-20ab9a4b8d20" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019e3c98-dd0b-7255-a419-20ab9a4b8d20_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019e3c98-dd0b-7255-a419-20ab9a4b8d20" xlink:to="loc_us-gaap_ClassOfStockDomain_019e3c98-dd0b-7255-a419-20ab9a4b8d20_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019e3c98-dd0b-7039-a6f2-5168960c50d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019e3c98-dd0b-7255-a419-20ab9a4b8d20" xlink:to="loc_us-gaap_ClassOfStockDomain_019e3c98-dd0b-7039-a6f2-5168960c50d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019e3c98-dd0b-7211-8a8f-3e4b34f12449" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e3c98-dd0b-7039-a6f2-5168960c50d3" xlink:to="loc_us-gaap_CommonStockMember_019e3c98-dd0b-7211-8a8f-3e4b34f12449" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_019e3c98-dd0b-7c92-97b2-fb8698c07bc8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e3c98-dd0b-7039-a6f2-5168960c50d3" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_019e3c98-dd0b-7c92-97b2-fb8698c07bc8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesBPreferredStockMember_019e3c98-dd0b-7ddc-a5a1-530fe0db9b2f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeriesBPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e3c98-dd0b-7039-a6f2-5168960c50d3" xlink:to="loc_us-gaap_SeriesBPreferredStockMember_019e3c98-dd0b-7ddc-a5a1-530fe0db9b2f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e3c98-dd0b-758b-8744-bd03dd6ca819" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_019e3c98-dd0b-78c7-b997-623f2d18e69e" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e3c98-dd0b-758b-8744-bd03dd6ca819" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e3c98-dd0b-758b-8744-bd03dd6ca819_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e3c98-dd0b-758b-8744-bd03dd6ca819" xlink:to="loc_us-gaap_EquityComponentDomain_019e3c98-dd0b-758b-8744-bd03dd6ca819_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e3c98-dd0b-7667-97d6-25125b297242" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e3c98-dd0b-758b-8744-bd03dd6ca819" xlink:to="loc_us-gaap_EquityComponentDomain_019e3c98-dd0b-7667-97d6-25125b297242" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019e3c98-dd0b-714e-9643-8837953ab94f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e3c98-dd0b-7667-97d6-25125b297242" xlink:to="loc_us-gaap_CommonStockMember_019e3c98-dd0b-714e-9643-8837953ab94f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_019e3c98-dd0b-734e-9e68-52864d603d51" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e3c98-dd0b-7667-97d6-25125b297242" xlink:to="loc_us-gaap_TreasuryStockCommonMember_019e3c98-dd0b-734e-9e68-52864d603d51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_019e3c98-dd0b-7901-8a8d-202be5d6612e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e3c98-dd0b-7a6f-97d8-1c7622c2193f" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_019e3c98-dd0b-7901-8a8d-202be5d6612e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_019e3c98-dd0b-75a4-a6f4-7e82a25e27dd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e3c98-dd0b-7a6f-97d8-1c7622c2193f" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_019e3c98-dd0b-75a4-a6f4-7e82a25e27dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_019e3c98-dd0b-7d76-a81d-9e63adc03137" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e3c98-dd0b-7a6f-97d8-1c7622c2193f" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_019e3c98-dd0b-7d76-a81d-9e63adc03137" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_019e3c98-dd0b-76f9-b497-9948ff2dfde8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e3c98-dd0b-7a6f-97d8-1c7622c2193f" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_019e3c98-dd0b-76f9-b497-9948ff2dfde8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesIssued_019e3c98-dd0b-7308-8703-79d4fbc4c318" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e3c98-dd0b-7a6f-97d8-1c7622c2193f" xlink:to="loc_us-gaap_PreferredStockSharesIssued_019e3c98-dd0b-7308-8703-79d4fbc4c318" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/ACCUMULATEDOTHERCOMPREHENSIVEINCOMEChangesinAOCIlossrelatedtoshareholdersequityDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#ACCUMULATEDOTHERCOMPREHENSIVEINCOMEChangesinAOCIlossrelatedtoshareholdersequityDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/ACCUMULATEDOTHERCOMPREHENSIVEINCOMEChangesinAOCIlossrelatedtoshareholdersequityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e3c98-dd0b-7e05-a87f-912b7427bc61" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e3c98-dd0b-7608-8f41-f7b23cb17e56" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e3c98-dd0b-7e05-a87f-912b7427bc61" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e3c98-dd0b-7608-8f41-f7b23cb17e56" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e3c98-dd0b-76dd-83f0-ed10bca9951f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e3c98-dd0b-7608-8f41-f7b23cb17e56" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e3c98-dd0b-76dd-83f0-ed10bca9951f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e3c98-dd0b-76dd-83f0-ed10bca9951f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e3c98-dd0b-76dd-83f0-ed10bca9951f" xlink:to="loc_us-gaap_EquityComponentDomain_019e3c98-dd0b-76dd-83f0-ed10bca9951f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e3c98-dd0b-74e1-a97b-736fca112f8e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e3c98-dd0b-76dd-83f0-ed10bca9951f" xlink:to="loc_us-gaap_EquityComponentDomain_019e3c98-dd0b-74e1-a97b-736fca112f8e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019e3c98-dd0b-7563-87b6-aa998ed277c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e3c98-dd0b-74e1-a97b-736fca112f8e" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019e3c98-dd0b-7563-87b6-aa998ed277c7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019e3c98-dd0b-7204-9b09-4fedc5d47402" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e3c98-dd0b-74e1-a97b-736fca112f8e" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019e3c98-dd0b-7204-9b09-4fedc5d47402" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_019e3c98-dd0b-73f2-bb8f-c181d8fe5ca5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e3c98-dd0b-74e1-a97b-736fca112f8e" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_019e3c98-dd0b-73f2-bb8f-c181d8fe5ca5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e3c98-dd0b-7468-b136-c72c00b1860f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e3c98-dd0b-74e1-a97b-736fca112f8e" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e3c98-dd0b-7468-b136-c72c00b1860f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_019e3c98-dd0b-7a9e-996d-2395e8edb879" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e3c98-dd0b-7608-8f41-f7b23cb17e56" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_019e3c98-dd0b-7a9e-996d-2395e8edb879" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019e3c98-dd0b-7a9e-996d-2395e8edb879_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019e3c98-dd0b-7a9e-996d-2395e8edb879" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019e3c98-dd0b-7a9e-996d-2395e8edb879_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019e3c98-dd0b-759b-8e12-c16759c9ae63" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019e3c98-dd0b-7a9e-996d-2395e8edb879" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019e3c98-dd0b-759b-8e12-c16759c9ae63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesMember_019e3c98-dd0b-7c01-866a-f006b93eae7a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019e3c98-dd0b-759b-8e12-c16759c9ae63" xlink:to="loc_us-gaap_SalesMember_019e3c98-dd0b-7c01-866a-f006b93eae7a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_019e3c98-dd0b-753f-9266-b3f08a92997a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019e3c98-dd0b-759b-8e12-c16759c9ae63" xlink:to="loc_us-gaap_CostOfSalesMember_019e3c98-dd0b-753f-9266-b3f08a92997a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e3c98-dd0b-724c-8a7a-d0be49c0061a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e3c98-dd0b-7e05-a87f-912b7427bc61" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e3c98-dd0b-724c-8a7a-d0be49c0061a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e3c98-dd0b-74af-962f-4f7f983f5357" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e3c98-dd0b-724c-8a7a-d0be49c0061a" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e3c98-dd0b-74af-962f-4f7f983f5357" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax_019e3c98-dd0b-7e79-b2fa-b60768e9bff5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e3c98-dd0b-724c-8a7a-d0be49c0061a" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax_019e3c98-dd0b-7e79-b2fa-b60768e9bff5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax_019e3c98-dd0b-7708-a9c8-187ad7bb6c2c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e3c98-dd0b-724c-8a7a-d0be49c0061a" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax_019e3c98-dd0b-7708-a9c8-187ad7bb6c2c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_019e3c98-dd0b-7ea4-b990-cac1c5d85a39" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e3c98-dd0b-724c-8a7a-d0be49c0061a" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_019e3c98-dd0b-7ea4-b990-cac1c5d85a39" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent_019e3c98-dd0b-7a8f-8240-3375537ee7c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e3c98-dd0b-724c-8a7a-d0be49c0061a" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent_019e3c98-dd0b-7a8f-8240-3375537ee7c8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodTax_019e3c98-dd0b-7d9e-83dc-524a21732e22" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAociCurrentPeriodTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e3c98-dd0b-724c-8a7a-d0be49c0061a" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodTax_019e3c98-dd0b-7d9e-83dc-524a21732e22" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_019e3c98-dd0b-7975-b719-b98ed3ad9852" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019e3c98-dd0b-724c-8a7a-d0be49c0061a" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_019e3c98-dd0b-7975-b719-b98ed3ad9852" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e3c98-dd0b-7e47-92a0-f1ea001ae653" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/VARIABLEINTERESTENTITIESDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#VARIABLEINTERESTENTITIESDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/VARIABLEINTERESTENTITIESDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityLineItems_019e3c98-dd0b-729d-8102-7e1d85605ecd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableInterestEntityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_019e3c98-dd0b-7f9a-9240-9260136144c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfVariableInterestEntitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e3c98-dd0b-729d-8102-7e1d85605ecd" xlink:to="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_019e3c98-dd0b-7f9a-9240-9260136144c2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e3c98-dd0b-7f2a-8d27-b8a9ba7467eb" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_019e3c98-dd0b-7f9a-9240-9260136144c2" xlink:to="loc_dei_LegalEntityAxis_019e3c98-dd0b-7f2a-8d27-b8a9ba7467eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e3c98-dd0b-7f2a-8d27-b8a9ba7467eb_default" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e3c98-dd0b-7f2a-8d27-b8a9ba7467eb" xlink:to="loc_dei_EntityDomain_019e3c98-dd0b-7f2a-8d27-b8a9ba7467eb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e3c98-dd0b-735d-b288-8eec6d438a29" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e3c98-dd0b-7f2a-8d27-b8a9ba7467eb" xlink:to="loc_dei_EntityDomain_019e3c98-dd0b-735d-b288-8eec6d438a29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_SunCokeMiddletownMember_019e3c98-dd0b-7e4b-9277-a50379df324c" xlink:href="clf-20260630.xsd#clf_SunCokeMiddletownMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019e3c98-dd0b-735d-b288-8eec6d438a29" xlink:to="loc_clf_SunCokeMiddletownMember_019e3c98-dd0b-7e4b-9277-a50379df324c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_019e3c98-dd0b-7809-bd5a-efedf464b28c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_019e3c98-dd0b-7f9a-9240-9260136144c2" xlink:to="loc_srt_ConsolidatedEntitiesAxis_019e3c98-dd0b-7809-bd5a-efedf464b28c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e3c98-dd0b-7809-bd5a-efedf464b28c_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e3c98-dd0b-7809-bd5a-efedf464b28c" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e3c98-dd0b-7809-bd5a-efedf464b28c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_019e3c98-dd0b-7aa0-a20e-d5a9a0d86bd7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_019e3c98-dd0b-7809-bd5a-efedf464b28c" xlink:to="loc_srt_ConsolidatedEntitiesDomain_019e3c98-dd0b-7aa0-a20e-d5a9a0d86bd7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_019e3c98-dd0b-7b73-bc28-cedca4302f45" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_019e3c98-dd0b-7aa0-a20e-d5a9a0d86bd7" xlink:to="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_019e3c98-dd0b-7b73-bc28-cedca4302f45" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019e3c98-dd0b-7f91-a630-b12510861677" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e3c98-dd0b-729d-8102-7e1d85605ecd" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019e3c98-dd0b-7f91-a630-b12510861677" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_019e3c98-dd0b-712a-b4a3-c1c5355159fd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e3c98-dd0b-729d-8102-7e1d85605ecd" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_019e3c98-dd0b-712a-b4a3-c1c5355159fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_019e3c98-dd0b-7ad8-8d2b-a69454061130" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InventoryNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e3c98-dd0b-729d-8102-7e1d85605ecd" xlink:to="loc_us-gaap_InventoryNet_019e3c98-dd0b-7ad8-8d2b-a69454061130" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019e3c98-dd0b-71d1-ba54-647f028e1863" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e3c98-dd0b-729d-8102-7e1d85605ecd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019e3c98-dd0b-71d1-ba54-647f028e1863" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_019e3c98-dd0b-7f9e-9650-f59d16b8e202" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e3c98-dd0b-729d-8102-7e1d85605ecd" xlink:to="loc_us-gaap_AccountsPayableCurrent_019e3c98-dd0b-7f9e-9650-f59d16b8e202" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_clf_OtherAssetsLiabilitiesNet_019e3c98-dd0b-7ba4-bc6a-99295bf6f73f" xlink:href="clf-20260630.xsd#clf_OtherAssetsLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e3c98-dd0b-729d-8102-7e1d85605ecd" xlink:to="loc_clf_OtherAssetsLiabilitiesNet_019e3c98-dd0b-7ba4-bc6a-99295bf6f73f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterest_019e3c98-dd0b-7c9f-8cea-efa86fa48468" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MinorityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_019e3c98-dd0b-729d-8102-7e1d85605ecd" xlink:to="loc_us-gaap_MinorityInterest_019e3c98-dd0b-7c9f-8cea-efa86fa48468" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/EARNINGSPERSHAREAntidilutiveSecuritiesDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#EARNINGSPERSHAREAntidilutiveSecuritiesDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/EARNINGSPERSHAREAntidilutiveSecuritiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019e3c98-dddc-761e-a07b-09f736a568cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019e3c98-dddc-7f8a-b611-217298da68ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019e3c98-dddc-761e-a07b-09f736a568cc" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019e3c98-dddc-7f8a-b611-217298da68ca" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019e3c98-dddc-7faa-8a4b-b658b0e98889" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019e3c98-dddc-7f8a-b611-217298da68ca" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019e3c98-dddc-7faa-8a4b-b658b0e98889" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e3c98-dddc-7faa-8a4b-b658b0e98889_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019e3c98-dddc-7faa-8a4b-b658b0e98889" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e3c98-dddc-7faa-8a4b-b658b0e98889_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e3c98-dddc-70ba-9efa-797e65f3436f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019e3c98-dddc-7faa-8a4b-b658b0e98889" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e3c98-dddc-70ba-9efa-797e65f3436f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockCompensationPlanMember_019e3c98-dddc-7547-aebc-1485e83c6a83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockCompensationPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019e3c98-dddc-70ba-9efa-797e65f3436f" xlink:to="loc_us-gaap_StockCompensationPlanMember_019e3c98-dddc-7547-aebc-1485e83c6a83" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019e3c98-dddc-7575-9eec-47d558d4cf81" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019e3c98-dddc-761e-a07b-09f736a568cc" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019e3c98-dddc-7575-9eec-47d558d4cf81" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.clevelandcliffs.com/role/COMMITMENTSANDCONTINGENCIESNarrativeDetails" xlink:type="simple" xlink:href="clf-20260630.xsd#COMMITMENTSANDCONTINGENCIESNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.clevelandcliffs.com/role/COMMITMENTSANDCONTINGENCIESNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_019e3c98-dddc-73ac-91fc-0b61b83bf75c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_019e3c98-dddc-7b97-935f-881cca0adf26" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e3c98-dddc-73ac-91fc-0b61b83bf75c" xlink:to="loc_us-gaap_OtherCommitmentsTable_019e3c98-dddc-7b97-935f-881cca0adf26" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsByNatureAxis_019e3c98-dddc-7de6-a868-ee1787b2ceff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsByNatureAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_019e3c98-dddc-7b97-935f-881cca0adf26" xlink:to="loc_us-gaap_GuaranteeObligationsByNatureAxis_019e3c98-dddc-7de6-a868-ee1787b2ceff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_019e3c98-dddc-7de6-a868-ee1787b2ceff_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_019e3c98-dddc-7de6-a868-ee1787b2ceff" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_019e3c98-dddc-7de6-a868-ee1787b2ceff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_019e3c98-dddc-7e06-8672-15dfb84cb212" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_019e3c98-dddc-7de6-a868-ee1787b2ceff" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_019e3c98-dddc-7e06-8672-15dfb84cb212" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SuretyBondMember_019e3c98-dddc-7b1c-812a-93ea33ee964b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SuretyBondMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain_019e3c98-dddc-7e06-8672-15dfb84cb212" xlink:to="loc_us-gaap_SuretyBondMember_019e3c98-dddc-7b1c-812a-93ea33ee964b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e3c98-dddc-717d-a26d-697612a54a9c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_019e3c98-dddc-7b97-935f-881cca0adf26" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e3c98-dddc-717d-a26d-697612a54a9c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dddc-717d-a26d-697612a54a9c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e3c98-dddc-717d-a26d-697612a54a9c" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dddc-717d-a26d-697612a54a9c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dddc-766a-b715-6bd3b87ba9ef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e3c98-dddc-717d-a26d-697612a54a9c" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dddc-766a-b715-6bd3b87ba9ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_019e3c98-dddc-71f2-bcaf-386d1d7dde54" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e3c98-dddc-766a-b715-6bd3b87ba9ef" xlink:to="loc_us-gaap_LetterOfCreditMember_019e3c98-dddc-71f2-bcaf-386d1d7dde54" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsMaximumExposure_019e3c98-dddc-736b-ac4d-02b229417b47" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsMaximumExposure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e3c98-dddc-73ac-91fc-0b61b83bf75c" xlink:to="loc_us-gaap_GuaranteeObligationsMaximumExposure_019e3c98-dddc-736b-ac4d-02b229417b47" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_019e3c98-dddc-701a-84d9-708fee4daaac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019e3c98-dddc-73ac-91fc-0b61b83bf75c" xlink:to="loc_us-gaap_LineOfCredit_019e3c98-dddc-701a-84d9-708fee4daaac" xlink:type="arc" order="1"/>
  </link:definitionLink>
</link:linkbase>
