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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2020-01-01</periodOfReport>

    <dateOfOriginalSubmission>2020-01-07</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001691303</issuerCik>
        <issuerName>WARRIOR MET COAL, INC.</issuerName>
        <issuerTradingSymbol>HCC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001419071</rptOwnerCik>
            <rptOwnerName>Boyles Dale W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>16243 HIGHWAY 216</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BROOKWOOD</rptOwnerCity>
            <rptOwnerState>AL</rptOwnerState>
            <rptOwnerZipCode>35444</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Financial Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-01-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1087</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>21.13</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>39484</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents the withholding of shares for tax purposes in connection with the vesting of restricted stock.</footnote>
        <footnote id="F2">Includes 6,278 shares of restricted stock granted to the reporting person on January 1, 2017 under the Warrior Met Coal, Inc. 2016 Equity Incentive Plan, which vest in equal installments on January 1, 2021 and January 1, 2022.</footnote>
    </footnotes>

    <remarks>This amendment corrects the direct holdings of the reporting person in Column 5 of Table I.  The original filing relating to the January 1, 2020 vesting event incorrectly reported the vesting of 3,137 shares as an acquisition of such shares, resulting in an overstatement of the amount of direct holdings by 3,137 shares.  Three subsequent Form 4 filings of the reporting person (filed February 11, 2020, February 18, 2020, and March 9, 2020) likewise overstated the direct holdings.</remarks>

    <ownerSignature>
        <signatureName>/s/ Kelli K. Gant, by power of attorney</signatureName>
        <signatureDate>2021-01-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
