diff --git a/packages/next/src/build/index.ts b/packages/next/src/build/index.ts
index c9925716d8a9b..3bc1c9eaef520 100644
--- a/packages/next/src/build/index.ts
+++ b/packages/next/src/build/index.ts
@@ -405,7 +405,7 @@ export default async function build(
       setGlobal('telemetry', telemetry)
 
       const publicDir = path.join(dir, 'public')
-      const isAppDirEnabled = !!config.experimental.appDir
+      const isAppDirEnabled = true
       const { pagesDir, appDir } = findPagesDir(dir, isAppDirEnabled)
       NextBuildContext.pagesDir = pagesDir
       NextBuildContext.appDir = appDir
diff --git a/packages/next/src/build/jest/jest.ts b/packages/next/src/build/jest/jest.ts
index db3c1a9c440cd..5bb279c17ebaa 100644
--- a/packages/next/src/build/jest/jest.ts
+++ b/packages/next/src/build/jest/jest.ts
@@ -73,7 +73,7 @@ export default function nextJest(options: { dir?: string } = {}) {
         isEsmProject = packageConfig.type === 'module'
 
         nextConfig = await getConfig(resolvedDir)
-        const isAppDirEnabled = !!nextConfig.experimental.appDir
+        const isAppDirEnabled = true
         const findPagesDirResult = findPagesDir(resolvedDir, isAppDirEnabled)
         hasServerComponents = !!findPagesDirResult.appDir
         pagesDir = findPagesDirResult.pagesDir
diff --git a/packages/next/src/build/webpack-config.ts b/packages/next/src/build/webpack-config.ts
index 21cf63283dc2d..f2bf6bd7923ff 100644
--- a/packages/next/src/build/webpack-config.ts
+++ b/packages/next/src/build/webpack-config.ts
@@ -293,12 +293,8 @@ export function getDefineEnv({
       config.reactStrictMode === null ? false : config.reactStrictMode
     ),
     'process.env.__NEXT_STRICT_MODE_APP': JSON.stringify(
-      // When next.config.js does not have reactStrictMode enabling appDir will enable it.
-      config.reactStrictMode === null
-        ? config.experimental.appDir
-          ? true
-          : false
-        : config.reactStrictMode
+      // When next.config.js does not have reactStrictMode it's enabled by default.
+      config.reactStrictMode === null ? true : config.reactStrictMode
     ),
     'process.env.__NEXT_OPTIMIZE_FONTS': JSON.stringify(
       !dev && config.optimizeFonts
@@ -791,7 +787,7 @@ export default async function getBaseWebpackConfig(
     rewrites.afterFiles.length > 0 ||
     rewrites.fallback.length > 0
 
-  const hasAppDir = !!config.experimental.appDir && !!appDir
+  const hasAppDir = !!appDir
   const hasServerComponents = hasAppDir
   const disableOptimizedLoading = true
   const enableTypedRoutes = !!config.experimental.typedRoutes && hasAppDir
@@ -2710,7 +2706,6 @@ export default async function getBaseWebpackConfig(
   }
 
   const configVars = JSON.stringify({
-    appDir: config.experimental.appDir,
     crossOrigin: config.crossOrigin,
     pageExtensions: pageExtensions,
     trailingSlash: config.trailingSlash,
diff --git a/packages/next/src/cli/next-lint.ts b/packages/next/src/cli/next-lint.ts
index e4832fc3c6f9d..3370cfc53397e 100755
--- a/packages/next/src/cli/next-lint.ts
+++ b/packages/next/src/cli/next-lint.ts
@@ -5,10 +5,7 @@ import { join } from 'path'
 import chalk from 'next/dist/compiled/chalk'
 
 import { CliCommand } from '../lib/commands'
-import {
-  ESLINT_DEFAULT_DIRS,
-  ESLINT_DEFAULT_DIRS_WITH_APP,
-} from '../lib/constants'
+import { ESLINT_DEFAULT_DIRS_WITH_APP } from '../lib/constants'
 import { runLintCheck } from '../lib/eslint/runLintCheck'
 import { printAndExit } from '../server/lib/utils'
 import { Telemetry } from '../telemetry/storage'
@@ -169,9 +166,7 @@ const nextLint: CliCommand = async (argv) => {
   const filesToLint = [...(dirs ?? []), ...files]
 
   // Remove that when the `appDir` will be stable.
-  const directoriesToLint = !!nextConfig.experimental.appDir
-    ? ESLINT_DEFAULT_DIRS_WITH_APP
-    : ESLINT_DEFAULT_DIRS
+  const directoriesToLint = ESLINT_DEFAULT_DIRS_WITH_APP
 
   const pathsToLint = (
     filesToLint.length ? filesToLint : directoriesToLint
@@ -190,11 +185,8 @@ const nextLint: CliCommand = async (argv) => {
 
   const distDir = join(baseDir, nextConfig.distDir)
   const defaultCacheLocation = join(distDir, 'cache', 'eslint/')
-  const hasAppDir = !!nextConfig.experimental.appDir
-  const { pagesDir, appDir } = findPagesDir(
-    baseDir,
-    !!nextConfig.experimental.appDir
-  )
+  const hasAppDir = true
+  const { pagesDir, appDir } = findPagesDir(baseDir, hasAppDir)
 
   await verifyTypeScriptSetup({
     dir: baseDir,
diff --git a/packages/next/src/export/index.ts b/packages/next/src/export/index.ts
index 37801f74bb6df..7e6c2f355c0c8 100644
--- a/packages/next/src/export/index.ts
+++ b/packages/next/src/export/index.ts
@@ -721,7 +721,7 @@ export default async function exportApp(
             httpAgentOptions: nextConfig.httpAgentOptions,
             debugOutput: options.debugOutput,
             isrMemoryCacheSize: nextConfig.experimental.isrMemoryCacheSize,
-            fetchCache: nextConfig.experimental.appDir,
+            fetchCache: true,
             fetchCacheKeyPrefix: nextConfig.experimental.fetchCacheKeyPrefix,
             incrementalCacheHandlerPath:
               nextConfig.experimental.incrementalCacheHandlerPath,
diff --git a/packages/next/src/lib/turbopack-warning.ts b/packages/next/src/lib/turbopack-warning.ts
index a7202f3208dcc..a54f6e732ebe8 100644
--- a/packages/next/src/lib/turbopack-warning.ts
+++ b/packages/next/src/lib/turbopack-warning.ts
@@ -20,7 +20,6 @@ const supportedTurbopackNextConfigOptions = [
   'swcMinify',
   'transpilePackages',
   'sassOptions.includePaths',
-  'experimental.appDir',
   'experimental.serverComponentsExternalPackages',
   'experimental.turbo',
   'experimental.mdxRs',
diff --git a/packages/next/src/server/base-server.ts b/packages/next/src/server/base-server.ts
index 5baafaa487ae4..2229e95293b94 100644
--- a/packages/next/src/server/base-server.ts
+++ b/packages/next/src/server/base-server.ts
@@ -426,8 +426,7 @@ export default abstract class Server<ServerOptions extends Options = Options> {
     this.buildId = this.getBuildId()
     this.minimalMode = minimalMode || !!process.env.NEXT_PRIVATE_MINIMAL_MODE
 
-    this.hasAppDir =
-      !!this.nextConfig.experimental.appDir && this.getHasAppDir(dev)
+    this.hasAppDir = this.getHasAppDir(dev)
     const serverComponents = this.hasAppDir
 
     this.nextFontManifest = this.getNextFontManifest()
@@ -1925,7 +1924,7 @@ export default abstract class Server<ServerOptions extends Options = Options> {
       const renderOpts: RenderOpts = {
         ...components,
         ...opts,
-        ...(isAppPath && this.nextConfig.experimental.appDir
+        ...(isAppPath
           ? {
               incrementalCache,
               isRevalidate: isSSG,
diff --git a/packages/next/src/server/dev/next-dev-server.ts b/packages/next/src/server/dev/next-dev-server.ts
index 985d283931bdf..a5860b9ef0fa1 100644
--- a/packages/next/src/server/dev/next-dev-server.ts
+++ b/packages/next/src/server/dev/next-dev-server.ts
@@ -180,19 +180,13 @@ export default class DevServer extends Server {
       })
     }
 
-    const { pagesDir, appDir } = findPagesDir(
-      this.dir,
-      !!this.nextConfig.experimental.appDir
-    )
+    const { pagesDir, appDir } = findPagesDir(this.dir, true)
     this.pagesDir = pagesDir
     this.appDir = appDir
   }
 
   protected getRouteMatchers(): RouteMatcherManager {
-    const { pagesDir, appDir } = findPagesDir(
-      this.dir,
-      !!this.nextConfig.experimental.appDir
-    )
+    const { pagesDir, appDir } = findPagesDir(this.dir, true)
 
     const ensurer: RouteEnsurer = {
       ensure: async (match) => {
diff --git a/packages/next/src/server/lib/route-resolver.ts b/packages/next/src/server/lib/route-resolver.ts
index 3334faee33393..83e122f2cc70a 100644
--- a/packages/next/src/server/lib/route-resolver.ts
+++ b/packages/next/src/server/lib/route-resolver.ts
@@ -66,10 +66,7 @@ export async function makeResolver(
     minimalMode: false,
     config: nextConfig,
   })
-  const { appDir, pagesDir } = findPagesDir(
-    dir,
-    !!nextConfig.experimental.appDir
-  )
+  const { appDir, pagesDir } = findPagesDir(dir, true)
   // we format the hostname so that it can be fetched
   const fetchHostname = formatHostname(hostname)
 
diff --git a/packages/next/src/server/lib/router-server.ts b/packages/next/src/server/lib/router-server.ts
index 4ee410d449672..44e73f698613f 100644
--- a/packages/next/src/server/lib/router-server.ts
+++ b/packages/next/src/server/lib/router-server.ts
@@ -104,10 +104,7 @@ export async function initialize(opts: {
     const telemetry = new Telemetry({
       distDir: path.join(opts.dir, config.distDir),
     })
-    const { pagesDir, appDir } = findPagesDir(
-      opts.dir,
-      !!config.experimental.appDir
-    )
+    const { pagesDir, appDir } = findPagesDir(opts.dir, true)
 
     const { setupDev } =
       (await require('./router-utils/setup-dev')) as typeof import('./router-utils/setup-dev')
diff --git a/packages/next/src/server/next-server.ts b/packages/next/src/server/next-server.ts
index 9bbfef0786a06..eef8514491d82 100644
--- a/packages/next/src/server/next-server.ts
+++ b/packages/next/src/server/next-server.ts
@@ -300,7 +300,7 @@ export default class NextNodeServer extends BaseServer {
         this.nextConfig.experimental.allowedRevalidateHeaderKeys,
       minimalMode: this.minimalMode,
       serverDistDir: this.serverDistDir,
-      fetchCache: this.nextConfig.experimental.appDir,
+      fetchCache: true,
       fetchCacheKeyPrefix: this.nextConfig.experimental.fetchCacheKeyPrefix,
       maxMemoryCacheSize: this.nextConfig.experimental.isrMemoryCacheSize,
       flushToDisk:
diff --git a/packages/next/src/server/web-server.ts b/packages/next/src/server/web-server.ts
index b347467d9ed43..525aa6b2c0c49 100644
--- a/packages/next/src/server/web-server.ts
+++ b/packages/next/src/server/web-server.ts
@@ -68,7 +68,7 @@ export default class NextWebServer extends BaseServer<WebServerOptions> {
       allowedRevalidateHeaderKeys:
         this.nextConfig.experimental.allowedRevalidateHeaderKeys,
       minimalMode: this.minimalMode,
-      fetchCache: this.nextConfig.experimental.appDir,
+      fetchCache: true,
       fetchCacheKeyPrefix: this.nextConfig.experimental.fetchCacheKeyPrefix,
       maxMemoryCacheSize: this.nextConfig.experimental.isrMemoryCacheSize,
       flushToDisk: false,