diff --git a/src/vs/workbench/contrib/chat/common/chatService/chatServiceImpl.ts b/src/vs/workbench/contrib/chat/common/chatService/chatServiceImpl.ts
index 5722b61e57000..ca2c905f8445c 100644
--- a/src/vs/workbench/contrib/chat/common/chatService/chatServiceImpl.ts
+++ b/src/vs/workbench/contrib/chat/common/chatService/chatServiceImpl.ts
@@ -243,6 +243,16 @@ export class ChatService extends Disposable implements IChatService {
 		const model = this._sessionModels.get(sessionResource);
 		if (model) {
 			model.setCustomTitle(title);
+		} else {
+			let modelRef: IChatModelReference | undefined;
+			try {
+				modelRef = await this.getOrRestoreSession(sessionResource);
+				modelRef?.object.setCustomTitle(title);
+			} catch (e) {
+				this.error('setChatSessionTitle', `Failed to restore session ${sessionResource} to set title: ${toErrorMessage(e)}`);
+			} finally {
+				modelRef?.dispose();
+			}
 		}
 
 		// Update the title in the file storage
diff --git a/src/vs/workbench/contrib/chat/common/model/chatModel.ts b/src/vs/workbench/contrib/chat/common/model/chatModel.ts
index a37c0e138ab19..0a32da92ffb3e 100644
--- a/src/vs/workbench/contrib/chat/common/model/chatModel.ts
+++ b/src/vs/workbench/contrib/chat/common/model/chatModel.ts
@@ -1211,6 +1211,7 @@ export interface IChatModel extends IDisposable {
 	readonly initialLocation: ChatAgentLocation;
 	readonly title: string;
 	readonly hasCustomTitle: boolean;
+	setCustomTitle(title: string): void;
 	/** True whenever a request is currently running */
 	readonly requestInProgress: IObservable<boolean>;
 	/** Provides session information when a request needs user interaction to continue */
diff --git a/src/vs/workbench/contrib/chat/test/common/model/mockChatModel.ts b/src/vs/workbench/contrib/chat/test/common/model/mockChatModel.ts
index 35ae57d3cc5bd..7671f3f779f92 100644
--- a/src/vs/workbench/contrib/chat/test/common/model/mockChatModel.ts
+++ b/src/vs/workbench/contrib/chat/test/common/model/mockChatModel.ts
@@ -54,6 +54,9 @@ export class MockChatModel extends Disposable implements IChatModel {
 		super.dispose();
 	}
 
+	setCustomTitle(title: string): void {
+		this.customTitle = title;
+	}
 	startEditingSession(isGlobalEditingSession?: boolean, transferFromSession?: IChatEditingSession): void { }
 	getRequests(): IChatRequestModel[] { return []; }
 	setCheckpoint(requestId: string | undefined): void { }