diff --git a/gulpfile.js b/gulpfile.js
index 6932e9cb82..7c8b8e7f6d 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -85,6 +85,7 @@ gulp.task('compile', function() {
     'lib/**/*.js',
     'lib/credential/index.d.ts',
     'lib/firebase-namespace-api.d.ts',
+    'lib/instance-id/index.d.ts',
     'lib/messaging/index.d.ts',
     'lib/remote-config/index.d.ts',
   ];
diff --git a/src/firebase-namespace-api.ts b/src/firebase-namespace-api.ts
index 248fe4b1df..679744b4c5 100644
--- a/src/firebase-namespace-api.ts
+++ b/src/firebase-namespace-api.ts
@@ -16,6 +16,7 @@
 
 import { Agent } from 'http';
 import { credential } from './credential/index';
+import { instanceId } from './instance-id/index';
 import { messaging } from './messaging/index';
 import { remoteConfig } from './remote-config/index';
 
@@ -214,6 +215,7 @@ export namespace app {
      */
     options: AppOptions;
 
+    instanceId(): instanceId.InstanceId;
     messaging(): messaging.Messaging;
     remoteConfig(): remoteConfig.RemoteConfig;
 
diff --git a/src/firebase-namespace.d.ts b/src/firebase-namespace.d.ts
index 7bf2d1dda4..4431bbcb89 100644
--- a/src/firebase-namespace.d.ts
+++ b/src/firebase-namespace.d.ts
@@ -16,5 +16,6 @@
 
 export * from './credential/index';
 export * from './firebase-namespace-api';
+export * from './instance-id/index';
 export * from './messaging/index';
 export * from './remote-config/index';
diff --git a/src/instance-id/index.ts b/src/instance-id/index.ts
index 8f984cdc4b..7ed4829ff0 100644
--- a/src/instance-id/index.ts
+++ b/src/instance-id/index.ts
@@ -14,24 +14,72 @@
  * limitations under the License.
  */
 
-import { FirebaseApp } from '../firebase-app';
-import * as instanceIdApi from './instance-id';
-
-export declare function instanceId(app?: FirebaseApp): instanceIdApi.InstanceId;
+import { app } from '../firebase-namespace-api';
 
 /**
- * We must define a namespace to make the typings work correctly. Otherwise
- * `admin.instanceId()` cannot be called like a function. Temporarily,
- * admin.instanceId is used as the namespace name because we cannot barrel
- * re-export the contents from instance-id, and we want it to
- * match the namespacing in the re-export inside src/index.d.ts
+ * Gets the {@link admin.instanceId.InstanceId `InstanceId`} service for the
+ * default app or a given app.
+ *
+ * `admin.instanceId()` can be called with no arguments to access the default
+ * app's {@link admin.instanceId.InstanceId `InstanceId`} service or as
+ * `admin.instanceId(app)` to access the
+ * {@link admin.instanceId.InstanceId `InstanceId`} service associated with a
+ * specific app.
+ *
+ * @example
+ * ```javascript
+ * // Get the Instance ID service for the default app
+ * var defaultInstanceId = admin.instanceId();
+ * ```
+ *
+ * @example
+ * ```javascript
+ * // Get the Instance ID service for a given app
+ * var otherInstanceId = admin.instanceId(otherApp);
+ *```
+ *
+ * @param app Optional app whose `InstanceId` service to
+ *   return. If not provided, the default `InstanceId` service will be
+ *   returned.
+ *
+ * @return The default `InstanceId` service if
+ *   no app is provided or the `InstanceId` service associated with the
+ *   provided app.
  */
+export declare function instanceId(app?: app.App): instanceId.InstanceId;
+
 /* eslint-disable @typescript-eslint/no-namespace */
-export namespace admin.instanceId {
-  // See https://github.com/microsoft/TypeScript/issues/4336
-  /* eslint-disable @typescript-eslint/no-unused-vars */
-  // See https://github.com/typescript-eslint/typescript-eslint/issues/363
-  // Allows for exposing classes as interfaces in typings
-  /* eslint-disable @typescript-eslint/no-empty-interface */
-  export interface InstanceId extends instanceIdApi.InstanceId {}
+export namespace instanceId {
+  /**
+   * Gets the {@link InstanceId `InstanceId`} service for the
+   * current app.
+   *
+   * @example
+   * ```javascript
+   * var instanceId = app.instanceId();
+   * // The above is shorthand for:
+   * // var instanceId = admin.instanceId(app);
+   * ```
+   *
+   * @return The `InstanceId` service for the
+   *   current app.
+   */
+  export interface InstanceId {
+    app: app.App;
+
+    /**
+     * Deletes the specified instance ID and the associated data from Firebase.
+     *
+     * Note that Google Analytics for Firebase uses its own form of Instance ID to
+     * keep track of analytics data. Therefore deleting a Firebase Instance ID does
+     * not delete Analytics data. See
+     * [Delete an Instance ID](/support/privacy/manage-iids#delete_an_instance_id)
+     * for more information.
+     *
+     * @param instanceId The instance ID to be deleted.
+     *
+     * @return A promise fulfilled when the instance ID is deleted.
+     */
+    deleteInstanceId(instanceId: string): Promise<void>;
+  }
 }
diff --git a/src/instance-id/instance-id.ts b/src/instance-id/instance-id.ts
index b17434e9a3..e09c630440 100644
--- a/src/instance-id/instance-id.ts
+++ b/src/instance-id/instance-id.ts
@@ -18,9 +18,11 @@ import { FirebaseApp } from '../firebase-app';
 import { FirebaseServiceInterface, FirebaseServiceInternalsInterface } from '../firebase-service';
 import { FirebaseInstanceIdError, InstanceIdClientErrorCode } from '../utils/error';
 import { FirebaseInstanceIdRequestHandler } from './instance-id-request-internal';
-
+import { instanceId } from './index';
 import * as validator from '../utils/validator';
 
+import InstanceIdInterface = instanceId.InstanceId;
+
 /**
  * Internals of an InstanceId service instance.
  */
@@ -50,7 +52,7 @@ class InstanceIdInternals implements FirebaseServiceInternalsInterface {
  * @return The `InstanceId` service for the
  *   current app.
  */
-export class InstanceId implements FirebaseServiceInterface {
+export class InstanceId implements FirebaseServiceInterface, InstanceIdInterface {
   public INTERNAL: InstanceIdInternals = new InstanceIdInternals();
 
   private app_: FirebaseApp;