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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2015-12-17</periodOfReport>

    <dateOfOriginalSubmission>2015-12-18</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001465128</issuerCik>
        <issuerName>STARWOOD PROPERTY TRUST, INC.</issuerName>
        <issuerTradingSymbol>STWD</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001373646</rptOwnerCik>
            <rptOwnerName>Sossen Andrew Jay</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O STARWOOD PROPERTY TRUST, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>591 WEST PUTNAM AVENUE</rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>COO and General Counsel</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2016-12-17</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>43725</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>110553</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The issuer granted restricted shares of the issuer's common stock (the &quot;Restricted Shares&quot;) to Mr. Sossen pursuant to the Starwood Property Trust, Inc. Equity Plan.  The Restricted Shares will vest as to Mr. Sossen in equal installments on the first two 18-month anniversaries of September 18, 2014, subject to certain conditions.</footnote>
        <footnote id="F2">This amendment corrects the number of restricted shares of the issuer's common stock granted on such date pursuant to the Starwood Property Trust, Inc. Equity Plan. In all other respects, the Form 4 remains unchanged.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Andrew J. Sossen</signatureName>
        <signatureDate>2016-03-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
