diff --git a/packages/bridge/src/capi.ts b/packages/bridge/src/capi.ts
index 623148d6a8..38056c42ce 100644
--- a/packages/bridge/src/capi.ts
+++ b/packages/bridge/src/capi.ts
@@ -1,4 +1,4 @@
-import { useNuxt, addPluginTemplate } from '@nuxt/kit'
+import { useNuxt, addPlugin, addPluginTemplate } from '@nuxt/kit'
 import { resolve } from 'upath'
 import { distDir } from './dirs'
 
@@ -14,6 +14,11 @@ export function setupCAPIBridge (_options: any) {
   nuxt.options.alias['@vue/composition-api'] = require.resolve('@vue/composition-api/dist/vue-composition-api.mjs')
   const capiPluginPath = resolve(distDir, 'runtime/capi.plugin.mjs')
   addPluginTemplate({ filename: 'capi.plugin.mjs', src: capiPluginPath })
+
+  // Add support for useNuxtApp
+  addPlugin(resolve(distDir, 'runtime/app.plugin.mjs'))
+
+  // Register Composition API before loading the rest of app
   nuxt.hook('webpack:config', (configs) => {
     // @ts-ignore
     configs.forEach(config => config.entry.app.unshift(capiPluginPath))
diff --git a/packages/bridge/src/runtime/app.mjs b/packages/bridge/src/runtime/app.mjs
deleted file mode 100644
index 5db30f7f4e..0000000000
--- a/packages/bridge/src/runtime/app.mjs
+++ /dev/null
@@ -1,5 +0,0 @@
-const mock = () => () => { throw new Error('not implemented') }
-
-export const defineNuxtPlugin = mock()
-export const defineNuxtComponent = mock()
-export const useNuxtApp = mock()
diff --git a/packages/bridge/src/runtime/app.plugin.mjs b/packages/bridge/src/runtime/app.plugin.mjs
new file mode 100644
index 0000000000..82c18b0ef4
--- /dev/null
+++ b/packages/bridge/src/runtime/app.plugin.mjs
@@ -0,0 +1,27 @@
+import { createHooks } from 'hookable/dist/index.mjs'
+import { setNuxtInstance } from '#app'
+
+export default (ctx, inject) => {
+  const nuxt = {
+    provide: inject,
+    globalName: 'nuxt',
+    payload: process.client ? ctx.nuxtState : ctx.ssrContext.nuxt,
+    isHydrating: ctx.isHMR,
+    legacyNuxt: ctx.app
+  }
+  nuxt.hooks = createHooks()
+  nuxt.hook = nuxt.hooks.hook
+  nuxt.callHook = nuxt.hooks.callHook
+
+  if (!Array.isArray(ctx.app.created)) {
+    ctx.app.created = [ctx.app.created]
+  }
+
+  ctx.app.created.push(function () {
+    nuxt.legacyApp = this
+  })
+
+  setNuxtInstance(nuxt)
+
+  inject('_nuxtApp', nuxt)
+}
diff --git a/packages/bridge/src/runtime/app.ts b/packages/bridge/src/runtime/app.ts
new file mode 100644
index 0000000000..9d183f3be7
--- /dev/null
+++ b/packages/bridge/src/runtime/app.ts
@@ -0,0 +1,59 @@
+import type { Hookable } from 'hookable'
+// @ts-ignore
+import type { Vue } from 'vue/types/vue'
+import type { ComponentOptions } from 'vue'
+import { defineComponent, getCurrentInstance } from './composables'
+
+export const defineNuxtComponent = defineComponent
+
+export interface RuntimeNuxtHooks { }
+
+export interface NuxtAppCompat {
+  legacyNuxt: Vue
+  legacyApp: ComponentOptions<Vue>
+
+  globalName: string
+
+  hooks: Hookable<RuntimeNuxtHooks>
+  hook: NuxtAppCompat['hooks']['hook']
+  callHook: NuxtAppCompat['hooks']['callHook']
+
+  [key: string]: any
+
+  ssrContext?: Record<string, any>
+  payload: {
+    [key: string]: any
+  }
+
+  provide: (name: string, value: any) => void
+}
+
+export interface Context {
+  // eslint-disable-next-line
+  $_nuxtApp: NuxtAppCompat
+}
+
+let currentNuxtInstance: NuxtAppCompat | null
+
+export const setNuxtInstance = (nuxt: NuxtAppCompat | null) => {
+  currentNuxtInstance = nuxt
+}
+
+export const defineNuxtPlugin = plugin => (ctx: Context) => {
+  setNuxtInstance(ctx.$_nuxtApp)
+  plugin(ctx.$_nuxtApp)
+  setNuxtInstance(null)
+}
+
+export const useNuxtApp = () => {
+  const vm = getCurrentInstance()
+
+  if (!vm) {
+    if (!currentNuxtInstance) {
+      throw new Error('nuxt instance unavailable')
+    }
+    return currentNuxtInstance
+  }
+
+  return vm?.proxy.$_nuxtApp
+}
diff --git a/packages/bridge/src/runtime/composables.mjs b/packages/bridge/src/runtime/composables.ts
similarity index 100%
rename from packages/bridge/src/runtime/composables.mjs
rename to packages/bridge/src/runtime/composables.ts
diff --git a/packages/nuxt3/src/app/nuxt.ts b/packages/nuxt3/src/app/nuxt.ts
index 983ebdcd0f..00e62c5db0 100644
--- a/packages/nuxt3/src/app/nuxt.ts
+++ b/packages/nuxt3/src/app/nuxt.ts
@@ -68,7 +68,6 @@ export function createNuxt (options: CreateOptions) {
   const nuxt: NuxtApp = {
     provide: undefined,
     globalName: 'nuxt',
-    state: {},
     payload: {},
     isHydrating: process.client,
     ...options