diff --git a/types/node/test/worker_threads.ts b/types/node/test/worker_threads.ts
index 94cf1df5202094e..60982438f7b5260 100644
--- a/types/node/test/worker_threads.ts
+++ b/types/node/test/worker_threads.ts
@@ -144,8 +144,12 @@ import { createContext } from "node:vm";
     bc.close();
     bc.ref();
     bc.unref();
-    bc.onmessage = (msg: unknown) => {};
-    bc.onmessageerror = (msg: unknown) => {};
+    bc.onmessage = (msg) => {
+        msg; // $ExpectType MessageEvent<any>
+    };
+    bc.onmessageerror = (msg) => {
+        msg; // $ExpectType MessageEvent<any>
+    };
 
     // Test global alias
     const bc2 = new BroadcastChannel("test");
diff --git a/types/node/v18/test/worker_threads.ts b/types/node/v18/test/worker_threads.ts
index 31d2b08702443b8..11a3c35e81d5242 100644
--- a/types/node/v18/test/worker_threads.ts
+++ b/types/node/v18/test/worker_threads.ts
@@ -128,8 +128,12 @@ import { createContext } from "node:vm";
     bc.close();
     bc.ref();
     bc.unref();
-    bc.onmessage = (msg: unknown) => {};
-    bc.onmessageerror = (msg: unknown) => {};
+    bc.onmessage = (msg) => {
+        msg; // $ExpectType MessageEvent<any>
+    };
+    bc.onmessageerror = (msg) => {
+        msg; // $ExpectType MessageEvent<any>
+    };
 
     // Test global alias
     const bc2 = new BroadcastChannel("test");
diff --git a/types/node/v18/worker_threads.d.ts b/types/node/v18/worker_threads.d.ts
index 484f457fb6fc723..de5244216cacb21 100644
--- a/types/node/v18/worker_threads.d.ts
+++ b/types/node/v18/worker_threads.d.ts
@@ -59,6 +59,7 @@ declare module "worker_threads" {
     import { Readable, Writable } from "node:stream";
     import { ReadableStream, TransformStream, WritableStream } from "node:stream/web";
     import { URL } from "node:url";
+    import { MessageEvent } from "undici-types";
     const isMainThread: boolean;
     const parentPort: null | MessagePort;
     const resourceLimits: ResourceLimits;
@@ -525,18 +526,18 @@ declare module "worker_threads" {
      * ```
      * @since v15.4.0
      */
-    class BroadcastChannel {
+    class BroadcastChannel extends EventTarget {
         readonly name: string;
         /**
          * Invoked with a single \`MessageEvent\` argument when a message is received.
          * @since v15.4.0
          */
-        onmessage: (message: unknown) => void;
+        onmessage: (message: MessageEvent) => void;
         /**
          * Invoked with a received message cannot be deserialized.
          * @since v15.4.0
          */
-        onmessageerror: (message: unknown) => void;
+        onmessageerror: (message: MessageEvent) => void;
         constructor(name: string);
         /**
          * Closes the `BroadcastChannel` connection.
diff --git a/types/node/v20/test/worker_threads.ts b/types/node/v20/test/worker_threads.ts
index aeaac9f9e56293a..9e67d8baf97cbd1 100644
--- a/types/node/v20/test/worker_threads.ts
+++ b/types/node/v20/test/worker_threads.ts
@@ -128,8 +128,12 @@ import { createContext } from "node:vm";
     bc.close();
     bc.ref();
     bc.unref();
-    bc.onmessage = (msg: unknown) => {};
-    bc.onmessageerror = (msg: unknown) => {};
+    bc.onmessage = (msg) => {
+        msg; // $ExpectType MessageEvent<any>
+    };
+    bc.onmessageerror = (msg) => {
+        msg; // $ExpectType MessageEvent<any>
+    };
 
     // Test global alias
     const bc2 = new BroadcastChannel("test");
diff --git a/types/node/v20/worker_threads.d.ts b/types/node/v20/worker_threads.d.ts
index 89603a84c9166b9..a580d08243a90f2 100644
--- a/types/node/v20/worker_threads.d.ts
+++ b/types/node/v20/worker_threads.d.ts
@@ -59,6 +59,7 @@ declare module "worker_threads" {
     import { Readable, Writable } from "node:stream";
     import { ReadableStream, TransformStream, WritableStream } from "node:stream/web";
     import { URL } from "node:url";
+    import { MessageEvent } from "undici-types";
     const isMainThread: boolean;
     const parentPort: null | MessagePort;
     const resourceLimits: ResourceLimits;
@@ -544,18 +545,18 @@ declare module "worker_threads" {
      * ```
      * @since v15.4.0
      */
-    class BroadcastChannel {
+    class BroadcastChannel extends EventTarget {
         readonly name: string;
         /**
          * Invoked with a single \`MessageEvent\` argument when a message is received.
          * @since v15.4.0
          */
-        onmessage: (message: unknown) => void;
+        onmessage: (message: MessageEvent) => void;
         /**
          * Invoked with a received message cannot be deserialized.
          * @since v15.4.0
          */
-        onmessageerror: (message: unknown) => void;
+        onmessageerror: (message: MessageEvent) => void;
         constructor(name: string);
         /**
          * Closes the `BroadcastChannel` connection.
diff --git a/types/node/v22/test/worker_threads.ts b/types/node/v22/test/worker_threads.ts
index 38c7648f246e01f..b666a7465ab4f40 100644
--- a/types/node/v22/test/worker_threads.ts
+++ b/types/node/v22/test/worker_threads.ts
@@ -144,8 +144,12 @@ import { createContext } from "node:vm";
     bc.close();
     bc.ref();
     bc.unref();
-    bc.onmessage = (msg: unknown) => {};
-    bc.onmessageerror = (msg: unknown) => {};
+    bc.onmessage = (msg) => {
+        msg; // $ExpectType MessageEvent<any>
+    };
+    bc.onmessageerror = (msg) => {
+        msg; // $ExpectType MessageEvent<any>
+    };
 
     // Test global alias
     const bc2 = new BroadcastChannel("test");
diff --git a/types/node/v22/worker_threads.d.ts b/types/node/v22/worker_threads.d.ts
index d48fbabf4d3c53e..75f64ce2a9cd26a 100644
--- a/types/node/v22/worker_threads.d.ts
+++ b/types/node/v22/worker_threads.d.ts
@@ -63,6 +63,7 @@ declare module "worker_threads" {
     import { ReadableStream, TransformStream, WritableStream } from "node:stream/web";
     import { URL } from "node:url";
     import { HeapInfo } from "node:v8";
+    import { MessageEvent } from "undici-types";
     const isInternalThread: boolean;
     const isMainThread: boolean;
     const parentPort: null | MessagePort;
@@ -573,18 +574,18 @@ declare module "worker_threads" {
      * ```
      * @since v15.4.0
      */
-    class BroadcastChannel {
+    class BroadcastChannel extends EventTarget {
         readonly name: string;
         /**
          * Invoked with a single \`MessageEvent\` argument when a message is received.
          * @since v15.4.0
          */
-        onmessage: (message: unknown) => void;
+        onmessage: (message: MessageEvent) => void;
         /**
          * Invoked with a received message cannot be deserialized.
          * @since v15.4.0
          */
-        onmessageerror: (message: unknown) => void;
+        onmessageerror: (message: MessageEvent) => void;
         constructor(name: string);
         /**
          * Closes the `BroadcastChannel` connection.
diff --git a/types/node/worker_threads.d.ts b/types/node/worker_threads.d.ts
index c0acdefb81da433..73446b174cb23c9 100644
--- a/types/node/worker_threads.d.ts
+++ b/types/node/worker_threads.d.ts
@@ -63,6 +63,7 @@ declare module "worker_threads" {
     import { ReadableStream, TransformStream, WritableStream } from "node:stream/web";
     import { URL } from "node:url";
     import { HeapInfo } from "node:v8";
+    import { MessageEvent } from "undici-types";
     const isInternalThread: boolean;
     const isMainThread: boolean;
     const parentPort: null | MessagePort;
@@ -574,18 +575,18 @@ declare module "worker_threads" {
      * ```
      * @since v15.4.0
      */
-    class BroadcastChannel {
+    class BroadcastChannel extends EventTarget {
         readonly name: string;
         /**
          * Invoked with a single \`MessageEvent\` argument when a message is received.
          * @since v15.4.0
          */
-        onmessage: (message: unknown) => void;
+        onmessage: (message: MessageEvent) => void;
         /**
          * Invoked with a received message cannot be deserialized.
          * @since v15.4.0
          */
-        onmessageerror: (message: unknown) => void;
+        onmessageerror: (message: MessageEvent) => void;
         constructor(name: string);
         /**
          * Closes the `BroadcastChannel` connection.
diff --git a/types/office-js-preview/index.d.ts b/types/office-js-preview/index.d.ts
index 540e3c45a6cbbdb..9a009605579bfa5 100644
--- a/types/office-js-preview/index.d.ts
+++ b/types/office-js-preview/index.d.ts
@@ -55823,9 +55823,6 @@ declare namespace Excel {
          * Queues up a command to load the specified properties of the object. You must call `context.sync()` before reading the properties.
          *
          * @param propertyNamesAndPaths `propertyNamesAndPaths.select` is a comma-delimited string that specifies the properties to load, and `propertyNamesAndPaths.expand` is a comma-delimited string that specifies the navigation properties to load.
-         *
-         * @remarks
-         * [Api set: ExcelApi 1.20]
          */
         load(propertyNamesAndPaths?: {
             select?: string;
@@ -55935,9 +55932,6 @@ declare namespace Excel {
          * Queues up a command to load the specified properties of the object. You must call `context.sync()` before reading the properties.
          *
          * @param propertyNamesAndPaths `propertyNamesAndPaths.select` is a comma-delimited string that specifies the properties to load, and `propertyNamesAndPaths.expand` is a comma-delimited string that specifies the navigation properties to load.
-         *
-         * @remarks
-         * [Api set: ExcelApi 1.20]
          */
         load(propertyNamesAndPaths?: {
             select?: string;
@@ -56024,9 +56018,6 @@ declare namespace Excel {
          * Queues up a command to load the specified properties of the object. You must call `context.sync()` before reading the properties.
          *
          * @param propertyNamesAndPaths `propertyNamesAndPaths.select` is a comma-delimited string that specifies the properties to load, and `propertyNamesAndPaths.expand` is a comma-delimited string that specifies the navigation properties to load.
-         *
-         * @remarks
-         * [Api set: ExcelApi 1.20]
          */
         load(propertyNamesAndPaths?: {
             select?: string;
@@ -56085,9 +56076,6 @@ declare namespace Excel {
          * Queues up a command to load the specified properties of the object. You must call `context.sync()` before reading the properties.
          *
          * @param propertyNamesAndPaths `propertyNamesAndPaths.select` is a comma-delimited string that specifies the properties to load, and `propertyNamesAndPaths.expand` is a comma-delimited string that specifies the navigation properties to load.
-         *
-         * @remarks
-         * [Api set: ExcelApi 1.20]
          */
         load(propertyNamesAndPaths?: {
             select?: string;
@@ -56153,9 +56141,6 @@ declare namespace Excel {
          * Queues up a command to load the specified properties of the object. You must call `context.sync()` before reading the properties.
          *
          * @param propertyNamesAndPaths `propertyNamesAndPaths.select` is a comma-delimited string that specifies the properties to load, and `propertyNamesAndPaths.expand` is a comma-delimited string that specifies the navigation properties to load.
-         *
-         * @remarks
-         * [Api set: ExcelApi 1.20]
          */
         load(propertyNamesAndPaths?: {
             select?: string;
@@ -56292,9 +56277,6 @@ declare namespace Excel {
          * Queues up a command to load the specified properties of the object. You must call `context.sync()` before reading the properties.
          *
          * @param propertyNamesAndPaths `propertyNamesAndPaths.select` is a comma-delimited string that specifies the properties to load, and `propertyNamesAndPaths.expand` is a comma-delimited string that specifies the navigation properties to load.
-         *
-         * @remarks
-         * [Api set: ExcelApi 1.20]
          */
         load(propertyNamesAndPaths?: {
             select?: string;
diff --git a/types/office-js/index.d.ts b/types/office-js/index.d.ts
index 6aeb8217d81162e..98d8f3fbd8c6ee5 100644
--- a/types/office-js/index.d.ts
+++ b/types/office-js/index.d.ts
@@ -51834,9 +51834,6 @@ declare namespace Excel {
          * Queues up a command to load the specified properties of the object. You must call `context.sync()` before reading the properties.
          *
          * @param propertyNamesAndPaths `propertyNamesAndPaths.select` is a comma-delimited string that specifies the properties to load, and `propertyNamesAndPaths.expand` is a comma-delimited string that specifies the navigation properties to load.
-         *
-         * @remarks
-         * [Api set: ExcelApi 1.20]
          */
         load(propertyNamesAndPaths?: {
             select?: string;