diff --git a/src/vs/vscode.d.ts b/src/vs/vscode.d.ts
index 3068ae60c11..18c06565eb9 100644
--- a/src/vs/vscode.d.ts
+++ b/src/vs/vscode.d.ts
@@ -11571,11 +11571,13 @@ declare module 'vscode' {
 
 		/**
 		 * Sends a message to the renderer.
-		 * @param editor Editor to target with the message
 		 * @param message Message to send
-		 * @returns a boolean indicating whether the message was successfully delivered
+		 * @param editor Editor to target with the message. If not provided, the
+		 * message is sent to all renderers.
+		 * @returns a boolean indicating whether the message was successfully
+		 * delivered to any renderer.
 		 */
-		postMessage(editor: NotebookEditor, message: any): Thenable<boolean>;
+		postMessage(message: any, editor?: NotebookEditor): Thenable<boolean>;
 	}
 
 	/**
diff --git a/src/vs/workbench/api/browser/mainThreadNotebookRenderers.ts b/src/vs/workbench/api/browser/mainThreadNotebookRenderers.ts
index 6ebc512ddbe..83a3578155e 100644
--- a/src/vs/workbench/api/browser/mainThreadNotebookRenderers.ts
+++ b/src/vs/workbench/api/browser/mainThreadNotebookRenderers.ts
@@ -23,7 +23,7 @@ export class MainThreadNotebookRenderers extends Disposable implements MainThrea
 		}));
 	}
 
-	$postMessage(editorId: string, rendererId: string, message: unknown): Promise<boolean> {
+	$postMessage(editorId: string | undefined, rendererId: string, message: unknown): Promise<boolean> {
 		return this.messaging.receiveMessage(editorId, rendererId, message);
 	}
 }
diff --git a/src/vs/workbench/api/common/extHost.protocol.ts b/src/vs/workbench/api/common/extHost.protocol.ts
index 8814c9286bf..dcc74a8d949 100644
--- a/src/vs/workbench/api/common/extHost.protocol.ts
+++ b/src/vs/workbench/api/common/extHost.protocol.ts
@@ -936,7 +936,7 @@ export interface MainThreadNotebookKernelsShape extends IDisposable {
 }
 
 export interface MainThreadNotebookRenderersShape extends IDisposable {
-	$postMessage(editorId: string, rendererId: string, message: unknown): Promise<boolean>;
+	$postMessage(editorId: string | undefined, rendererId: string, message: unknown): Promise<boolean>;
 }
 
 export interface MainThreadInteractiveShape extends IDisposable {
diff --git a/src/vs/workbench/api/common/extHostNotebookRenderers.ts b/src/vs/workbench/api/common/extHostNotebookRenderers.ts
index bef5da1273a..2b18b0d9f26 100644
--- a/src/vs/workbench/api/common/extHostNotebookRenderers.ts
+++ b/src/vs/workbench/api/common/extHostNotebookRenderers.ts
@@ -44,14 +44,15 @@ export class ExtHostNotebookRenderers implements ExtHostNotebookRenderersShape {
 
 				return this.getOrCreateEmitterFor(rendererId).event(wrappedListener, thisArg, disposables);
 			},
-			postMessage: (editorOrAlias, message) => {
-				const editor = notebookEditorVisible ? editorOrAlias : notebookEditorAliases.get(editorOrAlias);
-				const extHostEditor = editor && ExtHostNotebookEditor.apiEditorsToExtHost.get(editor);
-				if (!extHostEditor) {
-					throw new Error(`The first argument to postMessage() must be a NotebookEditor`);
+			postMessage: (message, editorOrAlias) => {
+				if (ExtHostNotebookEditor.apiEditorsToExtHost.has(message)) { // back compat for swapped args
+					[message, editorOrAlias] = [editorOrAlias, message];
 				}
 
-				return this.proxy.$postMessage(extHostEditor.id, rendererId, message);
+
+				const editor = notebookEditorVisible ? editorOrAlias : notebookEditorAliases.get(editorOrAlias!);
+				const extHostEditor = editor && ExtHostNotebookEditor.apiEditorsToExtHost.get(editor);
+				return this.proxy.$postMessage(extHostEditor?.id, rendererId, message);
 			},
 		};
 
diff --git a/src/vs/workbench/contrib/notebook/browser/notebookRendererMessagingServiceImpl.ts b/src/vs/workbench/contrib/notebook/browser/notebookRendererMessagingServiceImpl.ts
index eb7fe07898d..e94a907f93a 100644
--- a/src/vs/workbench/contrib/notebook/browser/notebookRendererMessagingServiceImpl.ts
+++ b/src/vs/workbench/contrib/notebook/browser/notebookRendererMessagingServiceImpl.ts
@@ -23,7 +23,12 @@ export class NotebookRendererMessagingService implements INotebookRendererMessag
 	constructor(@IExtensionService private readonly extensionService: IExtensionService) { }
 
 	/** @inheritdoc */
-	public receiveMessage(editorId: string, rendererId: string, message: unknown): Promise<boolean> {
+	public receiveMessage(editorId: string | undefined, rendererId: string, message: unknown): Promise<boolean> {
+		if (editorId === undefined) {
+			const sends = [...this.scopedMessaging.values()].map(e => e.receiveMessageHandler?.(rendererId, message));
+			return Promise.all(sends).then(s => s.some(s => !!s));
+		}
+
 		return this.scopedMessaging.get(editorId)?.receiveMessageHandler?.(rendererId, message) ?? Promise.resolve(false);
 	}
 
diff --git a/src/vs/workbench/contrib/notebook/common/notebookRendererMessagingService.ts b/src/vs/workbench/contrib/notebook/common/notebookRendererMessagingService.ts
index f5701025e74..4d5f5dc04f7 100644
--- a/src/vs/workbench/contrib/notebook/common/notebookRendererMessagingService.ts
+++ b/src/vs/workbench/contrib/notebook/common/notebookRendererMessagingService.ts
@@ -29,7 +29,7 @@ export interface INotebookRendererMessagingService {
 	/**
 	 * Called when the main thread gets a message for a renderer.
 	 */
-	receiveMessage(editorId: string, rendererId: string, message: unknown): Promise<boolean>;
+	receiveMessage(editorId: string | undefined, rendererId: string, message: unknown): Promise<boolean>;
 }
 
 export interface IScopedRendererMessaging extends IDisposable {