diff --git a/package.json b/package.json
index bd684a2..347abdf 100644
--- a/package.json
+++ b/package.json
@@ -66,6 +66,7 @@
     "@types/jest": "^29.5.3",
     "@types/node": "^20.10.0",
     "@types/supertest": "^2.0.12",
+    "@types/ws": "^8.5.10",
     "@whatwg-node/fetch": "^0.9.14",
     "eslint": "^8.55.0",
     "hono": "^3.11.7",
@@ -73,8 +74,10 @@
     "np": "^7.7.0",
     "publint": "^0.1.16",
     "supertest": "^6.3.3",
+    "superwstest": "^2.0.3",
     "ts-jest": "^29.1.1",
     "tsup": "^7.2.0",
-    "typescript": "^5.3.2"
+    "typescript": "^5.3.2",
+    "ws": "^8.16.0"
   }
 }
diff --git a/src/listener.ts b/src/listener.ts
index 1e02c5c..8a04f85 100644
--- a/src/listener.ts
+++ b/src/listener.ts
@@ -1,5 +1,7 @@
-import type { IncomingMessage, ServerResponse, OutgoingHttpHeaders } from 'node:http'
+import { ServerResponse } from 'node:http'
+import type { IncomingMessage, OutgoingHttpHeaders } from 'node:http'
 import type { Http2ServerRequest, Http2ServerResponse } from 'node:http2'
+import type { Socket } from 'node:net'
 import { newRequest } from './request'
 import { cacheKey } from './response'
 import type { FetchCallback } from './types'
@@ -56,6 +58,10 @@ const responseViaResponseObject = async (
   if (res instanceof Promise) {
     res = await res.catch(handleFetchError)
   }
+  
+  if (res.status === 101) {
+    return
+  }
 
   try {
     if (cacheKey in res) {
@@ -103,10 +109,13 @@ const responseViaResponseObject = async (
   }
 }
 
+type RequestListener = ReturnType<typeof getRequestListener>;
+
 export const getRequestListener = (fetchCallback: FetchCallback) => {
   return (
     incoming: IncomingMessage | Http2ServerRequest,
-    outgoing: ServerResponse | Http2ServerResponse
+    outgoing: ServerResponse | Http2ServerResponse,
+    env?: Record<string, unknown>
   ) => {
     let res
 
@@ -115,7 +124,11 @@ export const getRequestListener = (fetchCallback: FetchCallback) => {
     const req = newRequest(incoming)
 
     try {
-      res = fetchCallback(req) as Response | Promise<Response>
+      res = fetchCallback(req, env || {
+        incoming,
+        outgoing
+      }) as Response | Promise<Response>
+      
       if (cacheKey in res) {
         // synchronous, cacheable response
         return responseViaCache(res as Response, outgoing)
@@ -131,3 +144,13 @@ export const getRequestListener = (fetchCallback: FetchCallback) => {
     return responseViaResponseObject(res, outgoing)
   }
 }
+
+export const getUpgradeListener = (requestListener: RequestListener) => {
+  return (incoming: IncomingMessage, socket: Socket, head: Buffer) => {
+    const outgoing = new ServerResponse(incoming)
+    outgoing.assignSocket(socket)
+    requestListener(incoming, outgoing, {
+        incoming, outgoing, socket, head
+    })
+  }
+}
\ No newline at end of file
diff --git a/src/server.ts b/src/server.ts
index 3ee0d02..7d37797 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -1,15 +1,19 @@
 import { createServer as createServerHTTP } from 'node:http'
 import type { AddressInfo } from 'node:net'
-import { getRequestListener } from './listener'
+import { getRequestListener, getUpgradeListener } from './listener'
 import type { Options, ServerType } from './types'
 
 export const createAdaptorServer = (options: Options): ServerType => {
   const fetchCallback = options.fetch
+  const upgrade = options.upgrade !== false
   const requestListener = getRequestListener(fetchCallback)
   // ts will complain about createServerHTTP and createServerHTTP2 not being callable, which works just fine
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   const createServer: any = options.createServer || createServerHTTP
   const server: ServerType = createServer(options.serverOptions || {}, requestListener)
+  if (upgrade) {
+    server.on('upgrade', getUpgradeListener(requestListener))
+  }
   return server
 }
 
diff --git a/src/types.ts b/src/types.ts
index 94461b0..9c94bcc 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1,3 +1,4 @@
+
 import type { createServer, Server, ServerOptions as HttpServerOptions } from 'node:http'
 import type {
   createSecureServer as createSecureHttp2Server,
@@ -11,8 +12,9 @@ import type {
   createServer as createHttpsServer,
   ServerOptions as HttpsServerOptions,
 } from 'node:https'
+import type { Env } from 'hono'
 
-export type FetchCallback = (request: Request) => Promise<unknown> | unknown
+export type FetchCallback = (request: Request, env: Env) => Promise<unknown> | unknown
 
 export type NextHandlerOption = {
   fetch: FetchCallback
@@ -50,4 +52,5 @@ export type Options = {
   fetch: FetchCallback
   port?: number
   hostname?: string
+  upgrade?: boolean
 } & ServerOptions
diff --git a/test/server.test.ts b/test/server.test.ts
index dcfd4ef..74d3be3 100644
--- a/test/server.test.ts
+++ b/test/server.test.ts
@@ -1,12 +1,16 @@
 import fs from 'node:fs'
+import type { IncomingMessage } from 'node:http'
 import { createServer as createHttp2Server } from 'node:http2'
 import { createServer as createHTTPSServer } from 'node:https'
+import type { Socket } from 'node:net'
 import { Response as PonyfillResponse } from '@whatwg-node/fetch'
 import { Hono } from 'hono'
 import { basicAuth } from 'hono/basic-auth'
 import { compress } from 'hono/compress'
 import { poweredBy } from 'hono/powered-by'
 import request from 'supertest'
+import wsRequest from 'superwstest'
+import { WebSocketServer } from 'ws'
 import { createAdaptorServer } from '../src/server'
 
 describe('Basic', () => {
@@ -469,7 +473,6 @@ describe('HTTP2', () => {
   })
 
   it('Should return 200 response - GET /', async () => {
-    // @ts-expect-error: @types/supertest is not updated yet
     const res = await request(server, { http2: true }).get('/').trustLocalhost()
     expect(res.status).toBe(200)
     expect(res.headers['content-type']).toMatch(/text\/plain/)
@@ -518,3 +521,38 @@ describe('set child response to c.res', () => {
     expect(res.headers['content-type']).toMatch(/application\/json/)
   })
 })
+
+describe('upgrade websocket', () => {
+  const app = new Hono<{
+    Bindings: {
+      incoming: IncomingMessage;
+      socket: Socket;
+      head: Buffer;
+    }
+  }>()
+  const wsServer = new WebSocketServer({ noServer: true })
+  
+  class UpgradeResponse extends Response {
+    status = 101
+  }
+
+  app.use('/', async (c) => {
+    wsServer.handleUpgrade(c.env.incoming, c.env.socket, c.env.head, (ws) => {
+        ws.send('Hello World!')
+    })
+
+    return new UpgradeResponse()
+  })
+  
+  const server = createAdaptorServer(app)
+  
+  // 'superwstest' needs the server to be listening
+  beforeEach((done) => { server.listen(0, 'localhost', done) })
+  afterEach((done) => { server.close(done) })
+
+  it('Should send a WebSocket message - GET /', async () => {
+    await wsRequest(server)
+      .ws('/')
+      .expectText('Hello World!')
+  })
+})
\ No newline at end of file