diff --git a/src/plugins/fs_routes/mod.ts b/src/plugins/fs_routes/mod.ts
index 03add8d712b..ef37f183a1e 100644
--- a/src/plugins/fs_routes/mod.ts
+++ b/src/plugins/fs_routes/mod.ts
@@ -4,7 +4,7 @@ import type { WalkEntry } from "@std/fs/walk";
 import * as path from "@std/path";
 import type { RouteConfig } from "../../types.ts";
 import type { RouteHandler } from "../../handlers.ts";
-import type { MiddlewareFn } from "../../middlewares/mod.ts";
+import type { Middleware, MiddlewareFn } from "../../middlewares/mod.ts";
 import {
   type AsyncAnyComponent,
   renderMiddleware,
@@ -34,7 +34,8 @@ export interface FreshFsItem<State> {
   handlers?: RouteHandler<unknown, State>;
   default?:
     | AnyComponent<PageProps<unknown, State>>
-    | AsyncAnyComponent<PageProps<unknown, State>>;
+    | AsyncAnyComponent<PageProps<unknown, State>>
+    | Middleware<State>;
 }
 
 // deno-lint-ignore no-explicit-any
@@ -43,7 +44,9 @@ function isFreshFile<State>(mod: any): mod is FreshFsItem<State> {
       typeof mod.default === "function" ||
     typeof mod.config === "object" || typeof mod.handlers === "object" ||
     typeof mod.handlers === "function" || typeof mod.handler === "object" ||
-    typeof mod.handler === "function";
+    typeof mod.handler === "function" ||
+    (Array.isArray(mod.default) && mod.default.length > 0 &&
+      mod.default.every((item: unknown) => typeof item === "function"));
 }
 
 export interface FsRoutesOptions {
diff --git a/src/plugins/fs_routes/mod_test.tsx b/src/plugins/fs_routes/mod_test.tsx
index 1f36890dd7f..ac4fcf6ab7d 100644
--- a/src/plugins/fs_routes/mod_test.tsx
+++ b/src/plugins/fs_routes/mod_test.tsx
@@ -13,6 +13,7 @@ import { type HandlerByMethod, type HandlerFn, page } from "../../handlers.ts";
 import type { Method } from "../../router.ts";
 import { parseHtml } from "../../../tests/test_utils.tsx";
 import type { FreshContext } from "fresh";
+import { createDefine } from "../../define.ts";
 
 async function createServer<T>(
   files: Record<string, string | Uint8Array | FreshFsItem<T>>,
@@ -189,6 +190,25 @@ Deno.test("fsRoutes - middleware", async () => {
   expect(await res.text()).toEqual("ok");
 });
 
+Deno.test("fsRoutes - middleware using define", async () => {
+  const server = await createServer<{ text: string }>({
+    "routes/index.ts": { handler: (ctx) => new Response(ctx.state.text) },
+    "routes/_middleware.ts": {
+      default: createDefine<{ text: string }>()
+        .middleware(
+          (ctx) => {
+            ctx.state.text = "A";
+            return ctx.next();
+          },
+        ),
+    },
+  });
+
+  const res = await server.get("/");
+  expect(res.status).toEqual(200);
+  expect(await res.text()).toEqual("ok");
+});
+
 Deno.test("fsRoutes - nested middlewares", async () => {
   const server = await createServer<{ text: string }>({
     "routes/_middleware.ts": {
@@ -239,6 +259,34 @@ Deno.test("fsRoutes - middleware array", async () => {
   expect(doc.body.firstChild?.textContent).toEqual("ABC");
 });
 
+Deno.test("fsRoutes - middleware array using define", async () => {
+  const server = await createServer<{ text: string }>({
+    "routes/_middleware.ts": {
+      default: createDefine<{ text: string }>().middleware([
+        (ctx) => {
+          ctx.state.text = "A";
+          return ctx.next();
+        },
+        (ctx) => {
+          ctx.state.text += "B";
+          return ctx.next();
+        },
+      ]),
+    },
+    "routes/foo/_middleware.ts": {
+      handler: (ctx) => {
+        ctx.state.text += "C";
+        return ctx.next();
+      },
+    },
+    "routes/foo/index.ts": { default: (ctx) => <div>{ctx.state.text}</div> },
+  });
+
+  const res = await server.get("/foo");
+  const doc = parseHtml(await res.text());
+  expect(doc.body.firstChild?.textContent).toEqual("ABC");
+});
+
 Deno.test("fsRoutes - combined", async () => {
   const server = await createServer<{ text: string }>({
     "routes/foo/bar.ts": {