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

    <schemaVersion>X0305</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-03-22</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001387713</issuerCik>
        <issuerName>NEULION, INC.</issuerName>
        <issuerTradingSymbol>NLN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001260042</rptOwnerCik>
            <rptOwnerName>PATERSON SCOTT</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>NEULION, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>1600 OLD COUNTRY ROAD</rptOwnerStreet2>
            <rptOwnerCity>PLAINVIEW</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>11803</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Executive Vice Chairman</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-03-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>29000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.22</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>7316290</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>85000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By spouse</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Multiple same-way open market purchases effected on the same day within a one dollar price range are reported on this line. The figure in the price column is the weighted average purchase price for these transactions. These trades were executed on the Toronto Stock Exchange,and the purchase prices were in Canadian dollars. The purchase price per share for each trade was between Cdn$0.21 and Cdn$0.225. The
purchase prices were converted to US dollars using the Bank of Canada noon exchange rate on March 22, 2012 of 0.9997.</footnote>
        <footnote id="F2">Mr. Paterson disclaims beneficial ownership of these securities, and this report shall not be deemed an admission that Mr. Paterson is the beneficial owner of such securities for purposes of Section 16 or for any other purpose.</footnote>
        <footnote id="F3">The reporting person undertakes to provide, upon request by the Commission staff, NeuLion, Inc., or a security holder of NeuLion, Inc., full information regarding the number of shares purchased at each separate price.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Roy E. Reichbach, attorney-in-fact</signatureName>
        <signatureDate>2012-03-26</signatureDate>
    </ownerSignature>
</ownershipDocument>
