diff --git a/.changeset/light-goats-teach.md b/.changeset/light-goats-teach.md
new file mode 100644
index 00000000..bb4933eb
--- /dev/null
+++ b/.changeset/light-goats-teach.md
@@ -0,0 +1,5 @@
+---
+'@hono/node-ws': patch
+---
+
+Add a `CloseEvent` class to avoid exception "CloseEvent is not defined"
diff --git a/packages/node-ws/src/events.ts b/packages/node-ws/src/events.ts
new file mode 100644
index 00000000..539762b2
--- /dev/null
+++ b/packages/node-ws/src/events.ts
@@ -0,0 +1,32 @@
+interface CloseEventInit extends EventInit {
+    code?: number;
+    reason?: string;
+    wasClean?: boolean;
+}
+
+/**
+ * @link https://developer.mozilla.org/en-US/docs/Web/API/CloseEvent
+ */
+export const CloseEvent = globalThis.CloseEvent ?? class extends Event {
+    #eventInitDict
+
+    constructor(
+        type: string,
+        eventInitDict: CloseEventInit = {}
+    ) {
+        super(type, eventInitDict)
+        this.#eventInitDict = eventInitDict
+    }
+
+    get wasClean(): boolean {
+        return this.#eventInitDict.wasClean ?? false
+    }
+
+    get code(): number {
+        return this.#eventInitDict.code ?? 0
+    }
+
+    get reason(): string {
+        return this.#eventInitDict.reason ?? ''
+    }
+}
diff --git a/packages/node-ws/src/index.test.ts b/packages/node-ws/src/index.test.ts
index 5ab99312..9cb12cb0 100644
--- a/packages/node-ws/src/index.test.ts
+++ b/packages/node-ws/src/index.test.ts
@@ -13,6 +13,7 @@ describe('WebSocket helper', () => {
 
   beforeEach(async () => {
     app = new Hono()
+    
     ;({ injectWebSocket, upgradeWebSocket } = createNodeWebSocket({ app }))
 
     server = await new Promise<ServerType>((resolve) => {
@@ -108,6 +109,21 @@ describe('WebSocket helper', () => {
     connections.forEach((ws) => ws.close())
   })
 
+  it('CloseEvent should be executed without crash', async () => {
+    app.get(
+      '/',
+      upgradeWebSocket(() => ({
+        onClose() {
+          // doing some stuff here
+        },
+      }))
+    )
+
+    const ws = new WebSocket('ws://localhost:3030/')
+    await new Promise<void>((resolve) => ws.on('open', resolve))
+    ws.close()
+  })
+
   it('Should be able to send and receive binary content with good length', async () => {
     const mainPromise = new Promise<WSMessageReceive>((resolve) =>
       app.get(
@@ -126,7 +142,7 @@ describe('WebSocket helper', () => {
     await new Promise<void>((resolve) => ws.on('open', resolve))
     ws.send(binaryData)
 
-    const receivedMessage = await mainPromise;
+    const receivedMessage = await mainPromise
     expect(receivedMessage).toBeInstanceOf(Buffer)
     expect((receivedMessage as Buffer).byteLength).toBe(binaryData.length)
 
diff --git a/packages/node-ws/src/index.ts b/packages/node-ws/src/index.ts
index d95f704b..e8a45b8a 100644
--- a/packages/node-ws/src/index.ts
+++ b/packages/node-ws/src/index.ts
@@ -1,4 +1,3 @@
-import { Buffer } from 'buffer'
 import type { Server } from 'node:http'
 import type { Http2SecureServer, Http2Server } from 'node:http2'
 import type { Hono } from 'hono'
@@ -6,6 +5,7 @@ import type { UpgradeWebSocket, WSContext } from 'hono/ws'
 import type { WebSocket } from 'ws'
 import { WebSocketServer } from 'ws'
 import type { IncomingMessage } from 'http'
+import { CloseEvent } from './events'
 
 export interface NodeWebSocket {
   upgradeWebSocket: UpgradeWebSocket