diff --git a/.changeset/chilled-donkeys-report.md b/.changeset/chilled-donkeys-report.md
new file mode 100644
index 00000000..26cb7d1e
--- /dev/null
+++ b/.changeset/chilled-donkeys-report.md
@@ -0,0 +1,5 @@
+---
+'@hono/zod-openapi': patch
+---
+
+fix: Strict type checking of return values
diff --git a/packages/zod-openapi/package.json b/packages/zod-openapi/package.json
index 5d25c90f..1caa588d 100644
--- a/packages/zod-openapi/package.json
+++ b/packages/zod-openapi/package.json
@@ -38,12 +38,12 @@
   },
   "homepage": "https://github.com/honojs/middleware",
   "peerDependencies": {
-    "hono": ">=3.9.0",
+    "hono": ">=3.11.1",
     "zod": "3.*"
   },
   "devDependencies": {
     "@hono/zod-validator": "^0.1.11",
-    "hono": "^3.9.1",
+    "hono": "^3.11.1",
     "zod": "^3.22.1"
   },
   "dependencies": {
@@ -53,4 +53,4 @@
   "engines": {
     "node": ">=16.0.0"
   }
-}
+}
\ No newline at end of file
diff --git a/packages/zod-openapi/src/index.ts b/packages/zod-openapi/src/index.ts
index 204db79e..cbbaa38a 100644
--- a/packages/zod-openapi/src/index.ts
+++ b/packages/zod-openapi/src/index.ts
@@ -4,6 +4,7 @@ import type {
   ResponseConfig,
   RouteConfig,
   ZodContentObject,
+  ZodMediaTypeObject,
   ZodRequestBody,
 } from '@asteasolutions/zod-to-openapi'
 import {
@@ -150,11 +151,12 @@ type ConvertPathType<T extends string> = T extends `${infer Start}/{${infer Para
   ? `${Start}/:${Param}${ConvertPathType<Rest>}`
   : T
 
-type HandlerResponse<O> =
-  | TypedResponse<O>
-  | Promise<TypedResponse<O>>
+type HandlerTypedResponse<O> = TypedResponse<O> | Promise<TypedResponse<O>>
+type HandlerAllResponse<O> =
   | Response
   | Promise<Response>
+  | TypedResponse<O>
+  | Promise<TypedResponse<O>>
 
 export type OpenAPIHonoOptions<E extends Env> = {
   defaultHook?: Hook<any, E, any, any>
@@ -171,7 +173,23 @@ export type RouteHandler<
     InputTypeForm<R> &
     InputTypeJson<R>,
   P extends string = ConvertPathType<R['path']>
-> = Handler<E, P, I, HandlerResponse<OutputType<R>>>
+> = Handler<
+  E,
+  P,
+  I,
+  // If response type is defined, only TypedResponse is allowed.
+  R extends {
+    responses: {
+      [statusCode: string]: {
+        content: {
+          [mediaType: string]: ZodMediaTypeObject
+        }
+      }
+    }
+  }
+    ? HandlerTypedResponse<OutputType<R>>
+    : HandlerAllResponse<OutputType<R>>
+>
 
 export type RouteHook<
   R extends RouteConfig,
@@ -186,8 +204,8 @@ export type RouteHook<
 > = Hook<I, E, P, OutputType<R>>
 
 export type OpenAPIObjectConfigure<E extends Env, P extends string> =
-  OpenAPIObjectConfig |
-  ((context: Context<E, P>) => OpenAPIObjectConfig)
+  | OpenAPIObjectConfig
+  | ((context: Context<E, P>) => OpenAPIObjectConfig)
 
 export class OpenAPIHono<
   E extends Env = Env,
@@ -214,7 +232,23 @@ export class OpenAPIHono<
     P extends string = ConvertPathType<R['path']>
   >(
     route: R,
-    handler: Handler<E, P, I, HandlerResponse<OutputType<R>>>,
+    handler: Handler<
+      E,
+      P,
+      I,
+      // If response type is defined, only TypedResponse is allowed.
+      R extends {
+        responses: {
+          [statusCode: string]: {
+            content: {
+              [mediaType: string]: ZodMediaTypeObject
+            }
+          }
+        }
+      }
+        ? HandlerTypedResponse<OutputType<R>>
+        : HandlerAllResponse<OutputType<R>>
+    >,
     hook: Hook<I, E, P, OutputType<R>> | undefined = this.defaultHook
   ): OpenAPIHono<E, S & ToSchema<R['method'], P, I['in'], OutputType<R>>, BasePath> => {
     this.openAPIRegistry.registerPath(route)
diff --git a/packages/zod-openapi/test/index.test.ts b/packages/zod-openapi/test/index.test.ts
index b1592986..9817df97 100644
--- a/packages/zod-openapi/test/index.test.ts
+++ b/packages/zod-openapi/test/index.test.ts
@@ -622,6 +622,14 @@ describe('Types', () => {
     >
     expectTypeOf(appRoutes).toMatchTypeOf<H>
   })
+
+  // @ts-expect-error it should throw an error if the types are wrong
+  app.openapi(route, (c) => {
+    return c.jsonT({
+      id: '123', // should be number
+      message: 'Success',
+    })
+  })
 })
 
 describe('Routers', () => {
@@ -1140,7 +1148,7 @@ describe('Context can be accessible in the doc route', () => {
     }
   )
 
-  app.doc('/doc', context => ({
+  app.doc('/doc', (context) => ({
     openapi: '3.0.0',
     info: {
       version: '1.0.0',
@@ -1149,7 +1157,7 @@ describe('Context can be accessible in the doc route', () => {
   }))
 
   it('Should return with the title set as specified in env', async () => {
-    const res = await app.request('/doc', null, { TITLE: 'My API' })
+    const res = await app.request('/doc', {}, { TITLE: 'My API' })
     expect(res.status).toBe(200)
     expect(await res.json()).toEqual({
       openapi: '3.0.0',
diff --git a/yarn.lock b/yarn.lock
index 1dc603b5..a1c17075 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -6935,11 +6935,16 @@ heap-js@^2.2.0:
   resolved "https://registry.yarnpkg.com/heap-js/-/heap-js-2.3.0.tgz#8eed2cede31ec312aa696eef1d4df0565841f183"
   integrity sha512-E5303mzwQ+4j/n2J0rDvEPBN7GKjhis10oHiYOgjxsmxYgqG++hz9NyLLOXttzH8as/DyiBHYpUrJTZWYaMo8Q==
 
-hono@^3.0.0, hono@^3.1.0, hono@^3.1.2, hono@^3.1.5, hono@^3.5.1, hono@^3.5.2, hono@^3.5.8, hono@^3.7.2, hono@^3.7.3, hono@^3.9.1, hono@^3.9.2:
+hono@^3.0.0, hono@^3.1.0, hono@^3.1.2, hono@^3.1.5, hono@^3.5.1, hono@^3.5.2, hono@^3.5.8, hono@^3.7.2, hono@^3.7.3, hono@^3.9.2:
   version "3.9.2"
   resolved "https://registry.yarnpkg.com/hono/-/hono-3.9.2.tgz#db31a6ce733131ee16bce0c9bd031a0708ebe052"
   integrity sha512-180NOiMadqU3lGmN6ajPDZvZPWus3a9mtVaAUR9uG0SImngBwRLA8vbnV0oUfUAgFT4nX55sGV9dVA06OuikHA==
 
+hono@^3.11.1:
+  version "3.11.1"
+  resolved "https://registry.yarnpkg.com/hono/-/hono-3.11.1.tgz#2f5893ae02baf55e1c5ad1e5b3a75936e3942c88"
+  integrity sha512-8FNUh8p/dkw8qYFxy8IJA500iW9NSeuvuwRfLw0FGkE/blCxtqWqxWTB+NaLSK3qGpaudzKur6s40Q0kpO0E+w==
+
 hosted-git-info@^2.1.4:
   version "2.8.9"
   resolved "https://registry.yarnpkg.com/hosted-git-info/-/hosted-git-info-2.8.9.tgz#dffc0bf9a21c02209090f2aa69429e1414daf3f9"