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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3/A</documentType>

    <periodOfReport>2021-07-20</periodOfReport>

    <dateOfOriginalSubmission>2021-07-21</dateOfOriginalSubmission>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001281761</issuerCik>
        <issuerName>REGIONS FINANCIAL CORP</issuerName>
        <issuerTradingSymbol>RF</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001204987</rptOwnerCik>
            <rptOwnerName>JOHNSON JOIA M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P. O. BOX 10247</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BIRMINGHAM</rptOwnerCity>
            <rptOwnerState>AL</rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2450</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes></footnotes>

    <remarks>The reporting person's Form 3 filed on 7/21/2021 reported in Table I, Column 3 that 2,450 shares of Regions Financial Corporation (&quot;RF&quot;) are owned directly by the reporting person. However, the shares of RF are held in a trust, of which the reporting person is the trustee and the sole beneficiary. This Form 3/A is being filed to correctly reflect that the 2,450 shares of RF are owned indirectly by the reporting person.</remarks>

    <ownerSignature>
        <signatureName>Lachelle S. Koon - Attorney-in-Fact</signatureName>
        <signatureDate>2022-04-21</signatureDate>
    </ownerSignature>
</ownershipDocument>
