diff --git a/extensions/typescript-language-features/package.json b/extensions/typescript-language-features/package.json
index c6d2722d421..d5b9bb4df3c 100644
--- a/extensions/typescript-language-features/package.json
+++ b/extensions/typescript-language-features/package.json
@@ -8,7 +8,6 @@
   "license": "MIT",
   "aiKey": "AIF-d9b70cd4-b9f9-4d70-929b-a071c400b217",
   "enabledApiProposals": [
-    "markdownStringBaseUri",
     "resolvers",
     "workspaceTrust"
   ],
diff --git a/extensions/typescript-language-features/tsconfig.json b/extensions/typescript-language-features/tsconfig.json
index 883b4b81749..07d4066f89b 100644
--- a/extensions/typescript-language-features/tsconfig.json
+++ b/extensions/typescript-language-features/tsconfig.json
@@ -12,7 +12,6 @@
 		"../../src/vscode-dts/vscode.d.ts",
 		"../../src/vscode-dts/vscode.proposed.inlayHints.d.ts",
 		"../../src/vscode-dts/vscode.proposed.languageStatus.d.ts",
-		"../../src/vscode-dts/vscode.proposed.markdownStringBaseUri.d.ts",
 		"../../src/vscode-dts/vscode.proposed.resolvers.d.ts",
 		"../../src/vscode-dts/vscode.proposed.workspaceTrust.d.ts",
 	]
diff --git a/extensions/vscode-api-tests/package.json b/extensions/vscode-api-tests/package.json
index 9ea109c5afc..2d0e6e7df14 100644
--- a/extensions/vscode-api-tests/package.json
+++ b/extensions/vscode-api-tests/package.json
@@ -17,7 +17,6 @@
     "findTextInFiles",
     "fsChunks",
     "inlineCompletions",
-    "markdownStringBaseUri",
     "notebookCellExecutionState",
     "notebookConcatTextDocument",
     "notebookContentProvider",
diff --git a/src/vs/workbench/services/extensions/common/extensionsApiProposals.ts b/src/vs/workbench/services/extensions/common/extensionsApiProposals.ts
index caac26cff71..62b43285f2e 100644
--- a/src/vs/workbench/services/extensions/common/extensionsApiProposals.ts
+++ b/src/vs/workbench/services/extensions/common/extensionsApiProposals.ts
@@ -25,7 +25,6 @@ export const allApiProposals = Object.freeze({
 	idToken: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.idToken.d.ts',
 	inlineCompletions: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.inlineCompletions.d.ts',
 	ipc: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.ipc.d.ts',
-	markdownStringBaseUri: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.markdownStringBaseUri.d.ts',
 	notebookCellExecutionState: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.notebookCellExecutionState.d.ts',
 	notebookConcatTextDocument: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.notebookConcatTextDocument.d.ts',
 	notebookContentProvider: 'https://raw.githubusercontent.com/microsoft/vscode/main/src/vscode-dts/vscode.proposed.notebookContentProvider.d.ts',
diff --git a/src/vscode-dts/vscode.d.ts b/src/vscode-dts/vscode.d.ts
index 11868ce6243..c8dc07c81c2 100644
--- a/src/vscode-dts/vscode.d.ts
+++ b/src/vscode-dts/vscode.d.ts
@@ -2660,6 +2660,27 @@ declare module 'vscode' {
 		 */
 		supportHtml?: boolean;
 
+		/**
+		 * Uri that relative paths are resolved relative to.
+		 *
+		 * If the `baseUri` ends with `/`, it is considered a directory and relative paths in the markdown are resolved relative to that directory:
+		 *
+		 * ```ts
+		 * const md = new vscode.MarkdownString(`[link](./file.js)`);
+		 * md.baseUri = vscode.Uri.file('/path/to/dir/');
+		 * // Here 'link' in the rendered markdown resolves to '/path/to/dir/file.js'
+		 * ```
+		 *
+		 * If the `baseUri` is a file, relative paths in the markdown are resolved relative to the parent dir of that file:
+		 *
+		 * ```ts
+		 * const md = new vscode.MarkdownString(`[link](./file.js)`);
+		 * md.baseUri = vscode.Uri.file('/path/to/otherFile.js');
+		 * // Here 'link' in the rendered markdown resolves to '/path/to/file.js'
+		 * ```
+		 */
+		baseUri?: Uri;
+
 		/**
 		 * Creates a new markdown string with the given value.
 		 *
diff --git a/src/vscode-dts/vscode.proposed.markdownStringBaseUri.d.ts b/src/vscode-dts/vscode.proposed.markdownStringBaseUri.d.ts
deleted file mode 100644
index 19a85286f67..00000000000
--- a/src/vscode-dts/vscode.proposed.markdownStringBaseUri.d.ts
+++ /dev/null
@@ -1,32 +0,0 @@
-/*---------------------------------------------------------------------------------------------
- *  Copyright (c) Microsoft Corporation. All rights reserved.
- *  Licensed under the MIT License. See License.txt in the project root for license information.
- *--------------------------------------------------------------------------------------------*/
-
-declare module 'vscode' {
-
-	// https://github.com/microsoft/vscode/issues/142051
-
-	interface MarkdownString {
-		/**
-		 * Uri that relative paths are resolved relative to.
-		 *
-		 * If the `baseUri` ends with `/`, it is considered a directory and relative paths in the markdown are resolved relative to that directory:
-		 *
-		 * ```ts
-		 * const md = new vscode.MarkdownString(`[link](./file.js)`);
-		 * md.baseUri = vscode.Uri.file('/path/to/dir/');
-		 * // Here 'link' in the rendered markdown resolves to '/path/to/dir/file.js'
-		 * ```
-		 *
-		 * If the `baseUri` is a file, relative paths in the markdown are resolved relative to the parent dir of that file:
-		 *
-		 * ```ts
-		 * const md = new vscode.MarkdownString(`[link](./file.js)`);
-		 * md.baseUri = vscode.Uri.file('/path/to/otherFile.js');
-		 * // Here 'link' in the rendered markdown resolves to '/path/to/file.js'
-		 * ```
-		 */
-		baseUri?: Uri;
-	}
-}