diff --git a/packages/next/src/build/index.ts b/packages/next/src/build/index.ts
index b934157b42e65..f3c1d5d29378f 100644
--- a/packages/next/src/build/index.ts
+++ b/packages/next/src/build/index.ts
@@ -93,6 +93,10 @@ import {
   TurborepoAccessTraceResult,
   writeTurborepoAccessTraceResult,
 } from './turborepo-access-trace'
+import {
+  validateMiddlewareInSrcDir,
+  validateInstrumentationInSrcDir,
+} from './utils'
 
 import {
   eventBuildOptimize,
@@ -1157,6 +1161,19 @@ export default async function build(
 
       NextBuildContext.hasInstrumentationHook = hasInstrumentationHook
 
+      if (isSrcDir) {
+        for (const rootPath of rootPaths) {
+          if (rootPath.includes(MIDDLEWARE_FILENAME)) {
+            const pathWithoutExtension = rootPath.replace(/\.[^/.]+$/, '')
+            validateMiddlewareInSrcDir(pathWithoutExtension, isSrcDir)
+          }
+          if (rootPath.includes(INSTRUMENTATION_HOOK_FILENAME)) {
+            const pathWithoutExtension = rootPath.replace(/\.[^/.]+$/, '')
+            validateInstrumentationInSrcDir(pathWithoutExtension, isSrcDir)
+          }
+        }
+      }
+
       const previewProps: __ApiPreviewProps = await generatePreviewKeys({
         isBuild: true,
         distDir,
diff --git a/packages/next/src/build/utils.ts b/packages/next/src/build/utils.ts
index f3a74a59d170a..ac1484ea5bf6c 100644
--- a/packages/next/src/build/utils.ts
+++ b/packages/next/src/build/utils.ts
@@ -81,6 +81,8 @@ import { buildAppStaticPaths } from './static-paths/app'
 import { buildPagesStaticPaths } from './static-paths/pages'
 import type { PrerenderedRoute } from './static-paths/types'
 import type { CacheControl } from '../server/lib/cache-control'
+import { normalizePathSep } from '../shared/lib/page-path/normalize-path-sep'
+
 import { formatExpire, formatRevalidate } from './output/format'
 
 export type ROUTER_TYPE = 'pages' | 'app'
@@ -1821,6 +1823,46 @@ export class NestedMiddlewareError extends Error {
   }
 }
 
+export class SrcDirectoryError extends Error {
+  constructor(fileName: string, fileType: 'middleware' | 'instrumentation') {
+    super(
+      `${fileType === 'middleware' ? 'Middleware' : 'Instrumentation'} file found outside src directory.\n` +
+        `Found: ${fileName}\n` +
+        `When using the src directory, ${fileType} files must be placed inside the src directory.\n` +
+        `Please move your ${fileType} file to src/${fileType}.\n` +
+        `Read More - https://nextjs.org/docs/app/api-reference/file-conventions/src-folder`
+    )
+  }
+}
+
+export function validateMiddlewareInSrcDir(
+  fileName: string,
+  isSrcDir: boolean
+) {
+  const normalizedPath = normalizePathSep(fileName)
+  if (
+    isSrcDir &&
+    isMiddlewareFile(fileName) &&
+    !normalizedPath.startsWith('/src/')
+  ) {
+    throw new SrcDirectoryError(fileName, 'middleware')
+  }
+}
+
+export function validateInstrumentationInSrcDir(
+  fileName: string,
+  isSrcDir: boolean
+) {
+  const normalizedPath = normalizePathSep(fileName)
+  if (
+    isSrcDir &&
+    isInstrumentationHookFile(fileName) &&
+    !normalizedPath.startsWith('/src/')
+  ) {
+    throw new SrcDirectoryError(fileName, 'instrumentation')
+  }
+}
+
 export function getSupportedBrowsers(
   dir: string,
   isDevelopment: boolean
diff --git a/packages/next/src/server/lib/router-utils/setup-dev-bundler.ts b/packages/next/src/server/lib/router-utils/setup-dev-bundler.ts
index 20a9c98890155..c55a10af47900 100644
--- a/packages/next/src/server/lib/router-utils/setup-dev-bundler.ts
+++ b/packages/next/src/server/lib/router-utils/setup-dev-bundler.ts
@@ -64,6 +64,8 @@ import {
   isInstrumentationHookFile,
   getPossibleMiddlewareFilenames,
   getPossibleInstrumentationHookFilenames,
+  validateMiddlewareInSrcDir,
+  validateInstrumentationInSrcDir,
 } from '../../../build/utils'
 import { devPageFiles } from '../../../build/webpack/plugins/next-types-plugin/shared'
 import type { LazyRenderServerInstance } from '../router-server'
@@ -426,6 +428,8 @@ async function startWatcher(
         })
 
         if (isMiddlewareFile(rootFile)) {
+          validateMiddlewareInSrcDir(rootFile, opts.isSrcDir)
+          
           const staticInfo = await getStaticInfoIncludingLayouts({
             pageFilePath: fileName,
             config: nextConfig,
@@ -453,6 +457,8 @@ async function startWatcher(
           continue
         }
         if (isInstrumentationHookFile(rootFile)) {
+          validateInstrumentationInSrcDir(rootFile, opts.isSrcDir)
+          
           serverFields.actualInstrumentationHookFile = rootFile
           await propagateServerField(
             opts,
diff --git a/test/integration/src-dir-validation/next.config.js b/test/integration/src-dir-validation/next.config.js
new file mode 100644
index 0000000000000..f3bbebcc4dad4
--- /dev/null
+++ b/test/integration/src-dir-validation/next.config.js
@@ -0,0 +1,5 @@
+module.exports = {
+  experimental: {
+    appDir: false,
+  },
+}
diff --git a/test/integration/src-dir-validation/src/pages/index.js b/test/integration/src-dir-validation/src/pages/index.js
new file mode 100644
index 0000000000000..8f5129010b9b0
--- /dev/null
+++ b/test/integration/src-dir-validation/src/pages/index.js
@@ -0,0 +1,3 @@
+export default function Home() {
+  return <div>Hello World</div>
+}
diff --git a/test/integration/src-dir-validation/test/index.test.js b/test/integration/src-dir-validation/test/index.test.js
new file mode 100644
index 0000000000000..2b027fd764cd1
--- /dev/null
+++ b/test/integration/src-dir-validation/test/index.test.js
@@ -0,0 +1,59 @@
+/* eslint-env jest */
+
+import fs from 'fs-extra'
+import { join } from 'path'
+import { nextBuild, nextStart, findPort, killApp } from 'next-test-utils'
+
+const appDir = join(__dirname, '../')
+
+describe('Src Directory Validation', () => {
+  beforeEach(async () => {
+    await fs.remove(join(appDir, 'middleware.js')).catch(() => {})
+    await fs.remove(join(appDir, 'instrumentation.js')).catch(() => {})
+  })
+
+  afterEach(async () => {
+    await fs.remove(join(appDir, 'middleware.js')).catch(() => {})
+    await fs.remove(join(appDir, 'instrumentation.js')).catch(() => {})
+  })
+
+  it('should throw error when middleware is outside src directory', async () => {
+    await fs.writeFile(
+      join(appDir, 'middleware.js'),
+      `export function middleware() { return new Response('middleware') }`
+    )
+
+    const result = await nextBuild(appDir, [], { stderr: true, stdout: true })
+    expect(result.stderr + result.stdout).toContain('Middleware file found outside src directory')
+  })
+
+  it('should throw error when instrumentation is outside src directory', async () => {
+    await fs.writeFile(
+      join(appDir, 'instrumentation.js'),
+      `export function register() { console.log('instrumentation') }`
+    )
+
+    const result = await nextBuild(appDir, [], { stderr: true, stdout: true })
+    expect(result.stderr + result.stdout).toContain('Instrumentation file found outside src directory')
+  })
+
+  it('should work correctly when middleware is inside src directory', async () => {
+    await fs.writeFile(
+      join(appDir, 'src/middleware.js'),
+      `export function middleware() { return new Response('middleware') }`
+    )
+
+    const result = await nextBuild(appDir, [], { stderr: true, stdout: true })
+    expect(result.code).toBe(0)
+  })
+
+  it('should work correctly when instrumentation is inside src directory', async () => {
+    await fs.writeFile(
+      join(appDir, 'src/instrumentation.js'),
+      `export function register() { console.log('instrumentation') }`
+    )
+
+    const result = await nextBuild(appDir, [], { stderr: true, stdout: true })
+    expect(result.code).toBe(0)
+  })
+})