diff --git a/src/libs/actions/Report/index.ts b/src/libs/actions/Report/index.ts
index 81459c69d968..c3d3424dc9e8 100644
--- a/src/libs/actions/Report/index.ts
+++ b/src/libs/actions/Report/index.ts
@@ -1457,11 +1457,9 @@ function openReport(params: OpenReportActionParams) {
     const participantLoginList = participants.map((p) => p.login).filter((login) => !!login);
     // TODO: allPersonalDetails fallback should be removed in follow-up PRs https://github.com/Expensify/App/issues/73656
     const participantAccountIDList = participants.map((p) => p.accountID).filter((id): id is number => id !== undefined);
-    const optimisticReport = reportActionsExist(reportID)
-        ? {}
-        : {
-              reportName: allReports?.[`${ONYXKEYS.COLLECTION.REPORT}${reportID}`]?.reportName ?? CONST.REPORT.DEFAULT_REPORT_NAME,
-          };
+    const existingReportName = allReports?.[`${ONYXKEYS.COLLECTION.REPORT}${reportID}`]?.reportName;
+    const isCreatingNewReport = !isEmptyObject(newReportObject);
+    const optimisticReport: Partial<Pick<Report, 'reportName'>> = reportActionsExist(reportID) || !existingReportName ? {} : {reportName: existingReportName};
 
     const optimisticData: Array<
         OnyxUpdate<
@@ -1490,8 +1488,10 @@ function openReport(params: OpenReportActionParams) {
         },
     ];
 
-    // Only add the report update if optimisticReport has data
-    if (Object.keys(optimisticReport).length > 0) {
+    // We need a report update for both:
+    // 1) existing reports with a known name, and
+    // 2) new reports, because the new-report flow mutates optimisticData.at(0) into a SET on REPORT_<id>.
+    if (isCreatingNewReport || Object.keys(optimisticReport).length > 0) {
         optimisticData.unshift({
             onyxMethod: Onyx.METHOD.MERGE,
             key: `${ONYXKEYS.COLLECTION.REPORT}${reportID}`,
@@ -1691,7 +1691,6 @@ function openReport(params: OpenReportActionParams) {
     }
 
     // If we are creating a new report, we need to add the optimistic report data and a report action
-    const isCreatingNewReport = !isEmptyObject(newReportObject);
     if (isCreatingNewReport) {
         // Change the method to set for new reports because it doesn't exist yet, is faster,
         // and we need the data to be available when we navigate to the chat page
diff --git a/tests/actions/ReportTest.ts b/tests/actions/ReportTest.ts
index 722d9b9edf16..7ed79e3d459d 100644
--- a/tests/actions/ReportTest.ts
+++ b/tests/actions/ReportTest.ts
@@ -1159,6 +1159,56 @@ describe('actions/Report', () => {
         TestHelper.expectAPICommandToHaveBeenCalled(WRITE_COMMANDS.OPEN_REPORT, 1);
     });
 
+    it('should not optimistically inject default report name when report has no known name', async () => {
+        const REPORT_ID = 'openReport_noKnownName';
+
+        setHasRadio(false);
+        await waitForBatchedUpdates();
+
+        Report.openReport({
+            reportID: REPORT_ID,
+            introSelected: undefined,
+            betas: undefined,
+        });
+        await waitForBatchedUpdates();
+
+        const report = await getOnyxValue(`${ONYXKEYS.COLLECTION.REPORT}${REPORT_ID}`);
+        expect(report?.reportName).toBeUndefined();
+
+        setHasRadio(true);
+        await waitForBatchedUpdates();
+    });
+
+    it('should keep optimistic new report write on report collection key', async () => {
+        const REPORT_ID = 'openReport_newReportOptimistic';
+
+        setHasRadio(false);
+        await waitForBatchedUpdates();
+
+        Report.openReport({
+            reportID: REPORT_ID,
+            introSelected: undefined,
+            betas: undefined,
+            newReportObject: {
+                reportID: REPORT_ID,
+            },
+        });
+        await waitForBatchedUpdates();
+
+        const report = await getOnyxValue(`${ONYXKEYS.COLLECTION.REPORT}${REPORT_ID}`);
+        expect(report).toMatchObject({
+            reportID: REPORT_ID,
+            reportName: CONST.REPORT.DEFAULT_REPORT_NAME,
+        });
+
+        const loadingState = await getOnyxValue(`${ONYXKEYS.COLLECTION.RAM_ONLY_REPORT_LOADING_STATE}${REPORT_ID}`);
+        expect(loadingState).not.toHaveProperty('reportID');
+        expect(loadingState).not.toHaveProperty('reportName');
+
+        setHasRadio(true);
+        await waitForBatchedUpdates();
+    });
+
     it('openReport legacy preview fallback stores action under correct Onyx key and preserves existing actions', async () => {
         global.fetch = TestHelper.getGlobalFetchMock();