diff --git a/src/elements/content-uploader/ContentUploader.tsx b/src/elements/content-uploader/ContentUploader.tsx
index 4dabc98f51..b058a628c5 100644
--- a/src/elements/content-uploader/ContentUploader.tsx
+++ b/src/elements/content-uploader/ContentUploader.tsx
@@ -977,22 +977,41 @@ class ContentUploader extends Component<ContentUploaderProps, State> {
      */
     updateViewAndCollection(items: UploadItem[], callback?: () => void) {
         const {
+            enableModernizedUploads,
             isPartialUploadEnabled,
             isResumableUploadsEnabled,
             onComplete,
             useUploadsManager,
         }: ContentUploaderProps = this.props;
-        const someUploadIsInProgress = items.some(uploadItem => uploadItem.status !== STATUS_COMPLETE);
+        // When the modernized flow is on, canceled items are kept in the list
+        // but treated as terminal so they do not block completion logic. The
+        // legacy view/state machine sees canceled items as non-COMPLETE which
+        // would otherwise stall progress and emit a stale success notification.
+        const isTerminalForModernized = (uploadItem: UploadItem) =>
+            enableModernizedUploads && uploadItem.status === STATUS_CANCELED;
+        const someUploadIsInProgress = items.some(
+            uploadItem => uploadItem.status !== STATUS_COMPLETE && !isTerminalForModernized(uploadItem),
+        );
         const someUploadHasFailed = items.some(uploadItem => uploadItem.status === STATUS_ERROR);
         const allItemsArePending = !items.some(uploadItem => uploadItem.status !== STATUS_PENDING);
         const noFileIsPendingOrInProgress = items.every(
             uploadItem => uploadItem.status !== STATUS_PENDING && uploadItem.status !== STATUS_IN_PROGRESS,
         );
         const areAllItemsFinished = items.every(
-            uploadItem => uploadItem.status === STATUS_COMPLETE || uploadItem.status === STATUS_ERROR,
+            uploadItem =>
+                uploadItem.status === STATUS_COMPLETE ||
+                uploadItem.status === STATUS_ERROR ||
+                isTerminalForModernized(uploadItem),
         );
         const uploadItemsStatus = isResumableUploadsEnabled ? areAllItemsFinished : noFileIsPendingOrInProgress;
 
+        // In the modernized flow, suppress the completion notification when
+        // no item actually finished successfully (e.g. user canceled every
+        // upload). This prevents a misleading "upload complete" toast/callback
+        // from any of the onComplete call sites below.
+        const hasCompletedItem = items.some(uploadItem => uploadItem.status === STATUS_COMPLETE);
+        const shouldFireOnComplete = !enableModernizedUploads || hasCompletedItem;
+
         let view = '';
         if ((items && items.length === 0) || allItemsArePending) {
             view = VIEW_UPLOAD_EMPTY;
@@ -1001,7 +1020,9 @@ class ContentUploader extends Component<ContentUploaderProps, State> {
             view = VIEW_UPLOAD_SUCCESS;
 
             if (!useUploadsManager) {
-                onComplete(cloneDeep(filesToBeUploaded.map(item => item.boxFile)));
+                if (shouldFireOnComplete) {
+                    onComplete(cloneDeep(filesToBeUploaded.map(item => item.boxFile)));
+                }
                 // Reset item collection after successful upload
                 items = [];
             }
@@ -1013,7 +1034,9 @@ class ContentUploader extends Component<ContentUploaderProps, State> {
             view = VIEW_UPLOAD_SUCCESS;
 
             if (!useUploadsManager) {
-                onComplete(cloneDeep(items.map(item => item.boxFile)));
+                if (shouldFireOnComplete) {
+                    onComplete(cloneDeep(items.map(item => item.boxFile)));
+                }
                 // Reset item collection after successful upload
                 items = [];
             }
@@ -1023,7 +1046,9 @@ class ContentUploader extends Component<ContentUploaderProps, State> {
             if (this.isAutoExpanded) {
                 this.resetUploadManagerExpandState();
             } // Else manually expanded so don't close
-            onComplete(items);
+            if (shouldFireOnComplete) {
+                onComplete(items);
+            }
         }
 
         const state: Partial<State> = {
diff --git a/src/elements/content-uploader/__tests__/ContentUploader.test.js b/src/elements/content-uploader/__tests__/ContentUploader.test.js
index 4682cdf902..664346e49d 100644
--- a/src/elements/content-uploader/__tests__/ContentUploader.test.js
+++ b/src/elements/content-uploader/__tests__/ContentUploader.test.js
@@ -1026,6 +1026,72 @@ describe('elements/content-uploader/ContentUploader', () => {
                 expect(complete.api.cancel).not.toHaveBeenCalled();
             });
 
+            describe('updateViewAndCollection with canceled items', () => {
+                let onComplete;
+                let wrapper;
+                let instance;
+
+                beforeEach(() => {
+                    onComplete = jest.fn();
+                    wrapper = getWrapper({
+                        enableModernizedUploads: true,
+                        useUploadsManager: true,
+                        onComplete,
+                    });
+                    instance = wrapper.instance();
+                });
+
+                test('should not fire onComplete when all items are canceled (modernized)', () => {
+                    instance.updateViewAndCollection([
+                        { status: STATUS_CANCELED, file: { name: 'a' } },
+                        { status: STATUS_CANCELED, file: { name: 'b' } },
+                    ]);
+                    expect(onComplete).not.toHaveBeenCalled();
+                });
+
+                test('should fire onComplete when at least one item completes (modernized)', () => {
+                    instance.updateViewAndCollection([
+                        { status: STATUS_COMPLETE, file: { name: 'a' } },
+                        { status: STATUS_CANCELED, file: { name: 'b' } },
+                    ]);
+                    expect(onComplete).toHaveBeenCalled();
+                });
+
+                test('should treat canceled items as terminal and resolve to VIEW_UPLOAD_SUCCESS (modernized)', () => {
+                    instance.updateViewAndCollection([
+                        { status: STATUS_COMPLETE, file: { name: 'a' } },
+                        { status: STATUS_CANCELED, file: { name: 'b' } },
+                    ]);
+                    expect(wrapper.state('view')).toBe(VIEW_UPLOAD_SUCCESS);
+                });
+
+                test('should not fire onComplete on the partial-upload path when all items are canceled (modernized, no manager)', () => {
+                    onComplete = jest.fn();
+                    wrapper = getWrapper({
+                        enableModernizedUploads: true,
+                        isPartialUploadEnabled: true,
+                        useUploadsManager: false,
+                        onComplete,
+                    });
+                    wrapper.instance().updateViewAndCollection([
+                        { status: STATUS_CANCELED, file: { name: 'a' } },
+                        { status: STATUS_CANCELED, file: { name: 'b' } },
+                    ]);
+                    expect(onComplete).not.toHaveBeenCalled();
+                });
+
+                test('should preserve legacy behavior when modernized flag is off', () => {
+                    onComplete = jest.fn();
+                    wrapper = getWrapper({
+                        enableModernizedUploads: false,
+                        useUploadsManager: true,
+                        onComplete,
+                    });
+                    wrapper.instance().updateViewAndCollection([{ status: STATUS_COMPLETE, file: { name: 'a' } }]);
+                    expect(onComplete).toHaveBeenCalled();
+                });
+            });
+
             test('handleUploadsManagerRetryAll should restart errored and canceled items', () => {
                 const onClickRetry = jest.fn();
                 const wrapper = getWrapper({ enableModernizedUploads: true, onClickRetry });