diff --git a/src/vs/workbench/api/common/extHost.protocol.ts b/src/vs/workbench/api/common/extHost.protocol.ts
index a433e7d86d9..35d0c6481be 100644
--- a/src/vs/workbench/api/common/extHost.protocol.ts
+++ b/src/vs/workbench/api/common/extHost.protocol.ts
@@ -665,7 +665,7 @@ export interface ICellDto {
 	language: string;
 	cellKind: CellKind;
 	outputs: IOutput[];
-	metadata?: NotebookCellMetadata;
+	metadata: NotebookCellMetadata;
 }
 
 export type NotebookCellsSplice = [
diff --git a/src/vs/workbench/api/common/extHostNotebook.ts b/src/vs/workbench/api/common/extHostNotebook.ts
index 96012a5c028..72b8dc90e79 100644
--- a/src/vs/workbench/api/common/extHostNotebook.ts
+++ b/src/vs/workbench/api/common/extHostNotebook.ts
@@ -33,7 +33,7 @@ export class ExtHostCell implements vscode.NotebookCell {
 		public cellKind: CellKind,
 		public language: string,
 		outputs: any[],
-		public metadata: vscode.NotebookCellMetadata | undefined,
+		public metadata: vscode.NotebookCellMetadata,
 	) {
 		this.source = this._content.split(/\r|\n|\r\n/g);
 		this._outputs = outputs;
@@ -341,6 +341,10 @@ export class ExtHostNotebookDocument extends Disposable implements vscode.Notebo
 	}
 }
 
+const notebookCellMetadataDefaults: vscode.NotebookCellMetadata = {
+	editable: true
+};
+
 export class ExtHostNotebookEditor extends Disposable implements vscode.NotebookEditor {
 	private _viewColumn: vscode.ViewColumn | undefined;
 	private static _cellhandlePool: number = 0;
@@ -382,6 +386,10 @@ export class ExtHostNotebookEditor extends Disposable implements vscode.Notebook
 	createCell(content: string, language: string, type: CellKind, outputs: vscode.CellOutput[], metadata: vscode.NotebookCellMetadata | undefined): vscode.NotebookCell {
 		const handle = ExtHostNotebookEditor._cellhandlePool++;
 		const uri = CellUri.generate(this.document.uri, handle);
+		metadata = {
+			...notebookCellMetadataDefaults,
+			...(metadata || {})
+		};
 		const cell = new ExtHostCell(handle, uri, content, type, language, outputs, metadata);
 		return cell;
 	}
diff --git a/src/vs/workbench/contrib/notebook/browser/notebookBrowser.ts b/src/vs/workbench/contrib/notebook/browser/notebookBrowser.ts
index 7531d38820c..eda85b6e49b 100644
--- a/src/vs/workbench/contrib/notebook/browser/notebookBrowser.ts
+++ b/src/vs/workbench/contrib/notebook/browser/notebookBrowser.ts
@@ -73,7 +73,7 @@ export interface ICellViewModel {
 	runState: CellRunState;
 	focusMode: CellFocusMode;
 	getText(): string;
-	metadata: NotebookCellMetadata | undefined;
+	metadata: NotebookCellMetadata;
 }
 
 export interface INotebookEditor {
diff --git a/src/vs/workbench/contrib/notebook/browser/view/renderers/cellRenderer.ts b/src/vs/workbench/contrib/notebook/browser/view/renderers/cellRenderer.ts
index dca0b07d2c6..e6935bb44d5 100644
--- a/src/vs/workbench/contrib/notebook/browser/view/renderers/cellRenderer.ts
+++ b/src/vs/workbench/contrib/notebook/browser/view/renderers/cellRenderer.ts
@@ -203,7 +203,7 @@ export class MarkdownCellRenderer extends AbstractCellRenderer implements IListR
 
 			const contextKeyService = this.contextKeyService.createScoped(templateData.container);
 			contextKeyService.createKey(NOTEBOOK_CELL_TYPE_CONTEXT_KEY, 'markdown');
-			contextKeyService.createKey(NOTEBOOK_CELL_EDITABLE_CONTEXT_KEY, element.metadata?.editable);
+			contextKeyService.createKey(NOTEBOOK_CELL_EDITABLE_CONTEXT_KEY, element.metadata.editable);
 			contextKeyService.createKey(NOTEBOOK_EDITABLE_CONTEXT_KEY, this.notebookEditor.viewModel?.metadata?.editable);
 
 			const toolbarActions = this.getCellToolbarActions(contextKeyService);
@@ -344,7 +344,7 @@ export class CodeCellRenderer extends AbstractCellRenderer implements IListRende
 
 		const contextKeyService = this.contextKeyService.createScoped(templateData.container);
 		contextKeyService.createKey(NOTEBOOK_CELL_TYPE_CONTEXT_KEY, 'code');
-		contextKeyService.createKey(NOTEBOOK_CELL_EDITABLE_CONTEXT_KEY, element.metadata?.editable);
+		contextKeyService.createKey(NOTEBOOK_CELL_EDITABLE_CONTEXT_KEY, element.metadata.editable);
 		contextKeyService.createKey(NOTEBOOK_EDITABLE_CONTEXT_KEY, this.notebookEditor.viewModel?.metadata?.editable);
 
 		const toolbarActions = this.getCellToolbarActions(contextKeyService);
diff --git a/src/vs/workbench/contrib/notebook/common/model/notebookCellTextModel.ts b/src/vs/workbench/contrib/notebook/common/model/notebookCellTextModel.ts
index 6b05e1a0da0..99ca6e14730 100644
--- a/src/vs/workbench/contrib/notebook/common/model/notebookCellTextModel.ts
+++ b/src/vs/workbench/contrib/notebook/common/model/notebookCellTextModel.ts
@@ -39,7 +39,7 @@ export class NotebookCellTextModel implements ICell {
 		public language: string,
 		public cellKind: CellKind,
 		outputs: IOutput[],
-		public readonly metadata: NotebookCellMetadata | undefined
+		public readonly metadata: NotebookCellMetadata
 	) {
 		this._outputs = outputs;
 	}
diff --git a/src/vs/workbench/contrib/notebook/common/notebookCommon.ts b/src/vs/workbench/contrib/notebook/common/notebookCommon.ts
index a76f4cc9392..3a7c8b8fd30 100644
--- a/src/vs/workbench/contrib/notebook/common/notebookCommon.ts
+++ b/src/vs/workbench/contrib/notebook/common/notebookCommon.ts
@@ -130,7 +130,7 @@ export interface ICell {
 	language: string;
 	cellKind: CellKind;
 	outputs: IOutput[];
-	metadata?: NotebookCellMetadata;
+	metadata: NotebookCellMetadata;
 	onDidChangeOutputs?: Event<NotebookCellOutputsSplice[]>;
 	resolveTextBufferFactory(): PieceTreeTextBufferFactory;
 	// TODO@rebornix it should be later on replaced by moving textmodel resolution into CellTextModel
diff --git a/src/vs/workbench/contrib/notebook/test/notebookViewModel.test.ts b/src/vs/workbench/contrib/notebook/test/notebookViewModel.test.ts
index 5c3093c461f..d257f320283 100644
--- a/src/vs/workbench/contrib/notebook/test/notebookViewModel.test.ts
+++ b/src/vs/workbench/contrib/notebook/test/notebookViewModel.test.ts
@@ -41,8 +41,8 @@ suite('NotebookViewModel', () => {
 				assert.equal(viewModel.viewCells.length, 3);
 				assert.equal(viewModel.notebookDocument.cells.length, 3);
 				assert.equal(viewModel.getViewCellIndex(cell), 1);
-				assert.equal(viewModel.viewCells[0].metadata?.editable, true);
-				assert.equal(viewModel.viewCells[0].metadata?.editable, false);
+				assert.equal(viewModel.viewCells[0].metadata.editable, true);
+				assert.equal(viewModel.viewCells[1].metadata.editable, false);
 
 				viewModel.deleteCell(1, true);
 				assert.equal(viewModel.viewCells.length, 2);
diff --git a/src/vs/workbench/contrib/notebook/test/testNotebookEditor.ts b/src/vs/workbench/contrib/notebook/test/testNotebookEditor.ts
index dc57c7712c4..288eb71783c 100644
--- a/src/vs/workbench/contrib/notebook/test/testNotebookEditor.ts
+++ b/src/vs/workbench/contrib/notebook/test/testNotebookEditor.ts
@@ -26,6 +26,11 @@ export class TestCell implements ICell {
 	onDidChangeOutputs: Event<NotebookCellOutputsSplice[]> = this._onDidChangeOutputs.event;
 	private _isDirty: boolean = false;
 	private _outputs: IOutput[];
+
+	get metadata(): NotebookCellMetadata {
+		return { editable: true };
+	}
+
 	get outputs(): IOutput[] {
 		return this._outputs;
 	}