<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>5</documentType>

    <periodOfReport>2018-12-31</periodOfReport>

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    <form3HoldingsReported>0</form3HoldingsReported>

    <form4TransactionsReported>0</form4TransactionsReported>

    <issuer>
        <issuerCik>0001047127</issuerCik>
        <issuerName>AMKOR TECHNOLOGY, INC.</issuerName>
        <issuerTradingSymbol>AMKR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001158922</rptOwnerCik>
            <rptOwnerName>KIM SUSAN Y</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2045 EAST INNOVATION CIRCLE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>TEMPE</rptOwnerCity>
            <rptOwnerState>AZ</rptOwnerState>
            <rptOwnerZipCode>85284</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>Exhibit 99.1</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
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                <value>Common Stock</value>
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            </transactionTimeliness>
            <transactionAmounts>
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                </transactionShares>
                <transactionPricePerShare>
                    <value>10.11</value>
                </transactionPricePerShare>
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                </directOrIndirectOwnership>
                <natureOfOwnership>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
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                <transactionPricePerShare>
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                <transactionShares>
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                <transactionPricePerShare>
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        <nonDerivativeTransaction>
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        </nonDerivativeTransaction>
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        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
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                <transactionShares>
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                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
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            <securityTitle>
                <value>Common Stock</value>
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                <value></value>
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                <transactionShares>
                    <value>1139605</value>
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                <transactionPricePerShare>
                    <value>7.16</value>
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                <transactionAcquiredDisposedCode>
                    <value>D</value>
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                <sharesOwnedFollowingTransaction>
                    <value>34581825</value>
                    <footnoteId id="F10"/>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By self as trustee</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-10-08</value>
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            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
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            <transactionTimeliness>
                <value></value>
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            <transactionAmounts>
                <transactionShares>
                    <value>2000000</value>
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                <transactionPricePerShare>
                    <value>6.93</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
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                <sharesOwnedFollowingTransaction>
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                    <footnoteId id="F10"/>
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                <directOrIndirectOwnership>
                    <value>D</value>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-10-08</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F9"/>
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            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2000000</value>
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                <transactionPricePerShare>
                    <value>6.93</value>
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                <transactionAcquiredDisposedCode>
                    <value>A</value>
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            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>34581825</value>
                    <footnoteId id="F10"/>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By self as trustee</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">On February 21, 2018, the James J. Kim 2014 Qualified Annuity Trust U/A dated 10/13/14 distributed 63,880 shares to James J. Kim. James J. Kim and Susan Y. Kim are co-trustees.</footnote>
        <footnote id="F2">On March 13, 2018, the Susan Y. Kim 2012 Irrevocable Trust dated 7/26/12 distributed 2,779,777 shares to the Susan Y. Kim Family Trust under the Susan Y. Kim 2012 Irrevocable Trust dated 7/26/12.  Susan Y. Kim and John T. Kim are co-trustees.</footnote>
        <footnote id="F3">On March 23, 2018, John T. Kim transferred 1,789,775 shares of the Issuer's Common Stock to the Qualified Annuity Trust under the John T. Kim 2018 Irrevocable Trust Agreement dated 2/6/18. Susan Y. Kim and John T. Kim are co-trustees.</footnote>
        <footnote id="F4">On August 16, 2018, the Susan Y. Kim 2015 Irrevocable Trust U/A Dated 3/16/15 distributed 560,450 shares of the Company's Common Stock to Susan Y. Kim.  Susan Y. Kim and John T. Kim are co-trustees.</footnote>
        <footnote id="F5">On September 7, 2018, James J. Kim transferred 2,470,150 shares of the Issuer's Common Stock to the James J. Kim 2018-1 Qualified Annuity Trust U/A dtd 8/30/18. James J. Kim and Susan Y. Kim are co-trustees.</footnote>
        <footnote id="F6">On September 21, 2018, the James J. Kim 2013 Qualified Annuity Trust U/A Dated 5/17/13 distributed 941,223 shares of the Issuer's Common Stock to James J. Kim.  James J. Kim and Susan Y. Kim are co-trustees.</footnote>
        <footnote id="F7">On October 5, 2018, the James J. Kim 2013 Qualified Annuity Trust U/A Dated 5/17/13 distributed 1,139,605 shares of the Issuer's Common Stock to Susan Y. Kim.  James J. Kim and Susan Y. Kim are co-trustees.</footnote>
        <footnote id="F8">On October 5, 2018, the James J. Kim 2013 Qualified Annuity Trust U/A Dated 5/17/13 distributed 1,139,605 shares of the Issuer's Common Stock to John T. Kim.  James J. Kim and Susan Y. Kim are co-trustees.</footnote>
        <footnote id="F9">On October 8, 2018, Susan Y. Kim transferred 2,000,000 shares of the Issuer's Common Stock to the Qualified Annuity Trust under the Susan Y. Kim 2018-1 Irrevocable Trust Agreement dtd 8/29/18.  James J. Kim and Susan Y. Kim are co-trustees.</footnote>
        <footnote id="F10">The reporting person disclaims beneficial ownership of these securities, except to the extent of the reporting person's pecuniary interest therein, and this report shall not be deemed an admission that the reporting person is the beneficial owner of such securities, except to the extent of the reporting person's pecuniary interest therein, for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Jerry Allison, as Attorney in Fact</signatureName>
        <signatureDate>2019-02-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
