diff --git a/src/CONST.ts b/src/CONST.ts
index 5d75f43cedd9..652a38200ab1 100755
--- a/src/CONST.ts
+++ b/src/CONST.ts
@@ -482,6 +482,7 @@ const CONST = {
                 ADDCOMMENT: 'ADDCOMMENT',
                 CLOSED: 'CLOSED',
                 CREATED: 'CREATED',
+                SUBMITTED: 'SUBMITTED',
                 TASKEDITED: 'TASKEDITED',
                 TASKCANCELLED: 'TASKCANCELLED',
                 IOU: 'IOU',
diff --git a/src/libs/ReportUtils.js b/src/libs/ReportUtils.js
index a8e80101c07f..746ecb7e20a4 100644
--- a/src/libs/ReportUtils.js
+++ b/src/libs/ReportUtils.js
@@ -2202,6 +2202,9 @@ function getIOUReportActionMessage(iouReportID, type, total, comment, currency,
         case CONST.REPORT.ACTIONS.TYPE.APPROVED:
             iouMessage = `approved ${amount}`;
             break;
+        case CONST.REPORT.ACTIONS.TYPE.SUBMITTED:
+            iouMessage = `submitted ${amount}`;
+            break;
         case CONST.IOU.REPORT_ACTION_TYPE.CREATE:
             iouMessage = `requested ${amount}${comment && ` for ${comment}`}`;
             break;
@@ -2359,6 +2362,44 @@ function buildOptimisticApprovedReportAction(amount, currency, expenseReportID)
     };
 }
 
+/**
+ * Builds an optimistic SUBMITTED report action with a randomly generated reportActionID.
+ *
+ * @param {Number} amount
+ * @param {String} currency
+ * @param {Number} expenseReportID
+ *
+ * @returns {Object}
+ */
+function buildOptimisticSubmittedReportAction(amount, currency, expenseReportID) {
+    const originalMessage = {
+        amount,
+        currency,
+        expenseReportID,
+    };
+
+    return {
+        actionName: CONST.REPORT.ACTIONS.TYPE.SUBMITTED,
+        actorAccountID: currentUserAccountID,
+        automatic: false,
+        avatar: lodashGet(currentUserPersonalDetails, 'avatar', UserUtils.getDefaultAvatar(currentUserAccountID)),
+        isAttachment: false,
+        originalMessage,
+        message: getIOUReportActionMessage(expenseReportID, CONST.REPORT.ACTIONS.TYPE.SUBMITTED, Math.abs(amount), '', currency),
+        person: [
+            {
+                style: 'strong',
+                text: lodashGet(currentUserPersonalDetails, 'displayName', currentUserEmail),
+                type: 'TEXT',
+            },
+        ],
+        reportActionID: NumberUtils.rand64(),
+        shouldShow: true,
+        created: DateUtils.getDBTime(),
+        pendingAction: CONST.RED_BRICK_ROAD_PENDING_ACTION.ADD,
+    };
+}
+
 /**
  * Builds an optimistic report preview action with a randomly generated reportActionID.
  *
@@ -3837,6 +3878,7 @@ export {
     buildOptimisticEditedTaskReportAction,
     buildOptimisticIOUReport,
     buildOptimisticApprovedReportAction,
+    buildOptimisticSubmittedReportAction,
     buildOptimisticExpenseReport,
     buildOptimisticIOUReportAction,
     buildOptimisticReportPreview,
diff --git a/src/libs/actions/IOU.js b/src/libs/actions/IOU.js
index 960ce989cc3c..2c046bfc2a24 100644
--- a/src/libs/actions/IOU.js
+++ b/src/libs/actions/IOU.js
@@ -2106,6 +2106,80 @@ function approveMoneyRequest(expenseReport) {
     API.write('ApproveMoneyRequest', {reportID: expenseReport.reportID, approvedReportActionID: optimisticApprovedReportAction.reportActionID}, {optimisticData, successData, failureData});
 }
 
+/**
+ * @param {Object} expenseReport
+ */
+function submitReport(expenseReport) {
+    const optimisticSubmittedReportAction = ReportUtils.buildOptimisticSubmittedReportAction(expenseReport.total, expenseReport.currency, expenseReport.reportID);
+
+    const optimisticReportActionsData = {
+        onyxMethod: Onyx.METHOD.MERGE,
+        key: `${ONYXKEYS.COLLECTION.REPORT_ACTIONS}${expenseReport.reportID}`,
+        value: {
+            [optimisticSubmittedReportAction.reportActionID]: {
+                ...optimisticSubmittedReportAction,
+                pendingAction: CONST.RED_BRICK_ROAD_PENDING_ACTION.ADD,
+            },
+        },
+    };
+    const optimisticIOUReportData = {
+        onyxMethod: Onyx.METHOD.MERGE,
+        key: `${ONYXKEYS.COLLECTION.REPORT}${expenseReport.reportID}`,
+        value: {
+            ...expenseReport,
+            lastMessageText: optimisticSubmittedReportAction.message[0].text,
+            lastMessageHtml: optimisticSubmittedReportAction.message[0].html,
+            state: CONST.REPORT.STATE.SUBMITTED,
+            stateNum: CONST.REPORT.STATE_NUM.PROCESSING,
+            statusNum: CONST.REPORT.STATUS.SUBMITTED,
+        },
+    };
+    const optimisticData = [optimisticIOUReportData, optimisticReportActionsData];
+
+    const successData = [
+        {
+            onyxMethod: Onyx.METHOD.MERGE,
+            key: `${ONYXKEYS.COLLECTION.REPORT_ACTIONS}${expenseReport.reportID}`,
+            value: {
+                [optimisticSubmittedReportAction.reportActionID]: {
+                    pendingAction: null,
+                },
+            },
+        },
+    ];
+
+    const failureData = [
+        {
+            onyxMethod: Onyx.METHOD.MERGE,
+            key: `${ONYXKEYS.COLLECTION.REPORT_ACTIONS}${expenseReport.reportID}`,
+            value: {
+                [expenseReport.reportActionID]: {
+                    errors: ErrorUtils.getMicroSecondOnyxError('iou.error.other'),
+                },
+            },
+        },
+        {
+            onyxMethod: Onyx.METHOD.MERGE,
+            key: `${ONYXKEYS.COLLECTION.REPORT}${expenseReport.reportID}`,
+            value: {
+                state: CONST.REPORT.STATE.OPEN,
+                stateNum: CONST.REPORT.STATE_NUM.OPEN,
+            },
+        },
+    ];
+
+    API.write(
+        'SubmitReport',
+        {
+            reportID: expenseReport.reportID,
+            managerEmail: expenseReport.managerEmail,
+            managerAccountID: expenseReport.managerID,
+            reportActionID: optimisticSubmittedReportAction.reportActionID,
+        },
+        {optimisticData, successData, failureData},
+    );
+}
+
 /**
  * @param {String} paymentType
  * @param {Object} chatReport
@@ -2327,10 +2401,6 @@ function getIOUReportID(iou, route) {
     return lodashGet(route, 'params.reportID') || lodashGet(iou, 'participants.0.reportID', '');
 }
 
-function submitReport() {
-    // Will be implemented in https://github.com/Expensify/App/issues/28763
-}
-
 export {
     createDistanceRequest,
     editMoneyRequest,
@@ -2340,6 +2410,7 @@ export {
     requestMoney,
     sendMoneyElsewhere,
     approveMoneyRequest,
+    submitReport,
     payMoneyRequest,
     sendMoneyWithWallet,
     startMoneyRequest,
@@ -2362,5 +2433,4 @@ export {
     updateDistanceRequest,
     replaceReceipt,
     getIOUReportID,
-    submitReport,
 };