diff --git a/.changeset/thin-spies-watch.md b/.changeset/thin-spies-watch.md
new file mode 100644
index 0000000..acfca0b
--- /dev/null
+++ b/.changeset/thin-spies-watch.md
@@ -0,0 +1,5 @@
+---
+'@hono/vite-dev-server': minor
+---
+
+feat: support `cf` property in Cloudflare adapter
diff --git a/packages/dev-server/e2e/e2e.test.ts b/packages/dev-server/e2e/e2e.test.ts
index cfe3659..59d36bd 100644
--- a/packages/dev-server/e2e/e2e.test.ts
+++ b/packages/dev-server/e2e/e2e.test.ts
@@ -95,3 +95,9 @@ test('Should not throw an error if accessing the `caches`', async ({ page }) =>
   // It does **not** return cached content.
   expect(await resCached?.text()).not.toBe('cached')
 })
+
+test('Should set `cf` properties', async ({ page }) => {
+  const res = await page.goto('/cf')
+  expect(res?.ok()).toBe(true)
+  expect(await res?.json()).toEqual({ cf: true })
+})
diff --git a/packages/dev-server/e2e/mock/worker.ts b/packages/dev-server/e2e/mock/worker.ts
index 5158269..56044cc 100644
--- a/packages/dev-server/e2e/mock/worker.ts
+++ b/packages/dev-server/e2e/mock/worker.ts
@@ -92,4 +92,11 @@ app.get('/cache', async (c) => {
   return c.text('first')
 })
 
+app.get('/cf', (c) => {
+  return c.json({
+    // @ts-expect-error `Request.cf` is not typed
+    cf: typeof c.req.raw.cf === 'object' ? true : false,
+  })
+})
+
 export default app
diff --git a/packages/dev-server/src/adapter/cloudflare.ts b/packages/dev-server/src/adapter/cloudflare.ts
index 6a4892f..0e5872f 100644
--- a/packages/dev-server/src/adapter/cloudflare.ts
+++ b/packages/dev-server/src/adapter/cloudflare.ts
@@ -16,6 +16,7 @@ export const cloudflareAdapter: (options?: CloudflareAdapterOptions) => Promise<
   proxy ??= await getPlatformProxy(options?.proxy)
   // Cache API provided by `getPlatformProxy` currently do nothing.
   Object.assign(globalThis, { caches: proxy.caches })
+
   if (typeof globalThis.navigator === 'undefined') {
     // @ts-expect-error not typed well
     globalThis.navigator = {
@@ -28,6 +29,14 @@ export const cloudflareAdapter: (options?: CloudflareAdapterOptions) => Promise<
     })
   }
 
+  Object.defineProperty(Request.prototype, 'cf', {
+    get: function () {
+      return proxy.cf
+    },
+    configurable: true,
+    enumerable: true,
+  })
+
   return {
     env: proxy.env,
     executionContext: proxy.ctx,