diff --git a/.changeset/modern-buttons-impress.md b/.changeset/modern-buttons-impress.md
new file mode 100644
index 00000000..920c5f05
--- /dev/null
+++ b/.changeset/modern-buttons-impress.md
@@ -0,0 +1,5 @@
+---
+"@hono/zod-openapi": patch
+---
+
+fix(zod-openapi): return type of handler should be MaybePromise
diff --git a/packages/zod-openapi/src/index.ts b/packages/zod-openapi/src/index.ts
index 57b3eb25..4372975c 100644
--- a/packages/zod-openapi/src/index.ts
+++ b/packages/zod-openapi/src/index.ts
@@ -27,12 +27,14 @@ import type {
   TypedResponse,
 } from 'hono'
 import type { MergePath, MergeSchemaPath } from 'hono/types'
-import { StatusCode } from 'hono/utils/http-status'
+import type { StatusCode } from 'hono/utils/http-status'
 import type { Prettify, RemoveBlankRecord } from 'hono/utils/types'
 import { mergePath } from 'hono/utils/url'
 import type { AnyZodObject, ZodSchema, ZodError } from 'zod'
 import { z, ZodType } from 'zod'
 
+type MaybePromise<T> = Promise<T> | T
+
 type RouteConfig = RouteConfigBase & {
   middleware?: MiddlewareHandler | MiddlewareHandler[]
 }
@@ -290,8 +292,8 @@ export class OpenAPIHono<
           }
         }
       }
-        ? RouteConfigToTypedResponse<R>
-        : RouteConfigToTypedResponse<R> | Response | Promise<Response>
+        ? MaybePromise<RouteConfigToTypedResponse<R>>
+        : MaybePromise<RouteConfigToTypedResponse<R>> | MaybePromise<Response>
     >,
     hook:
       | Hook<
diff --git a/packages/zod-openapi/test/handler.test-d.ts b/packages/zod-openapi/test/handler.test-d.ts
new file mode 100644
index 00000000..2eaf5429
--- /dev/null
+++ b/packages/zod-openapi/test/handler.test-d.ts
@@ -0,0 +1,34 @@
+import { OpenAPIHono, createRoute, z } from '../src'
+
+test('supports async handler', () => {
+  const hono = new OpenAPIHono()
+
+  const route = createRoute({
+    method: 'get',
+    path: '/users',
+    responses: {
+      200: {
+        content: {
+          'application/json': {
+            schema: z.object({
+              id: z.string(),
+            }),
+          },
+        },
+        description: 'Retrieve the user',
+      },
+    },
+  })
+
+  hono.openapi(route, (c) => {
+    return c.json({
+      id: '123',
+    })
+  })
+
+  hono.openapi(route, async (c) => {
+    return c.json({
+      id: '123',
+    })
+  })
+})