diff --git a/docs/.ja/guide/advanced/composition.md b/docs/.ja/guide/advanced/composition.md
index b0a48ac71..989a61dc5 100644
--- a/docs/.ja/guide/advanced/composition.md
+++ b/docs/.ja/guide/advanced/composition.md
@@ -508,7 +508,6 @@ Below is the mapping table:
 | `datetimeFormats` | `datetimeFormats` |
 | `numberFormats` | `numberFormats` |
 | `modifiers` | `modifiers` |
-| `formatter` | N/A |
 | `missing` | `getMissingHandler` / `setMissingHandler` |
 | `postTranslation` | `getPostTranslationHandler` / `setPostTranslationHandler`|
 | `silentTranslationWarn` | `missingWarn` |
diff --git a/docs/guide/advanced/composition.md b/docs/guide/advanced/composition.md
index 53f49311a..559b35642 100644
--- a/docs/guide/advanced/composition.md
+++ b/docs/guide/advanced/composition.md
@@ -477,7 +477,6 @@ Below is the mapping table:
 | `datetimeFormats` | `datetimeFormats` |
 | `numberFormats` | `numberFormats` |
 | `modifiers` | `modifiers` |
-| `formatter` | N/A |
 | `missing` | `getMissingHandler` / `setMissingHandler` |
 | `postTranslation` | `getPostTranslationHandler` / `setPostTranslationHandler`|
 | `silentTranslationWarn` | `missingWarn` |
diff --git a/docs/guide/migration/breaking.md b/docs/guide/migration/breaking.md
index b1ed71210..44f83dbef 100644
--- a/docs/guide/migration/breaking.md
+++ b/docs/guide/migration/breaking.md
@@ -306,6 +306,10 @@ console.log(VueI18n.availability)
 
 **Reason**: Due to hard to provide custom formats in the new compiler and runtime APIs. We are planning to support it in the next major version to support in these APIs. If you would like to use ICU message format, you can use the [@formatjs/vue-intl](https://formatjs.io/docs/vue-intl/)
 
+> [!CAUTION]
+> `formatter` option implementation code is be going to fully remove in v10.
+> As an alternative, vue-i18n has the [custome message format](../advanced/format.md) as an experimental feature.
+
 ### Remove `preserveDirectiveContent` option
 
 The `v-t` directive for Vue 3 now preserves the default content. Therefore, this option and its properties have been removed from the VueI18n instance.
diff --git a/packages/petite-vue-i18n/src/index.ts b/packages/petite-vue-i18n/src/index.ts
index 2d66a1786..83de93bd2 100644
--- a/packages/petite-vue-i18n/src/index.ts
+++ b/packages/petite-vue-i18n/src/index.ts
@@ -81,7 +81,6 @@ export {
   WarnHtmlInMessageLevel,
   DateTimeFormatResult,
   NumberFormatResult,
-  Formatter,
   VueI18nOptions,
   VueI18n,
   VueI18nTranslation,
diff --git a/packages/petite-vue-i18n/src/runtime.ts b/packages/petite-vue-i18n/src/runtime.ts
index bb14a391b..3f624402d 100644
--- a/packages/petite-vue-i18n/src/runtime.ts
+++ b/packages/petite-vue-i18n/src/runtime.ts
@@ -73,7 +73,6 @@ export {
   WarnHtmlInMessageLevel,
   DateTimeFormatResult,
   NumberFormatResult,
-  Formatter,
   VueI18nOptions,
   VueI18n,
   VueI18nTranslation,
diff --git a/packages/vue-i18n-core/src/index.ts b/packages/vue-i18n-core/src/index.ts
index 14a69f958..0e194ca79 100644
--- a/packages/vue-i18n-core/src/index.ts
+++ b/packages/vue-i18n-core/src/index.ts
@@ -63,7 +63,6 @@ export {
   WarnHtmlInMessageLevel,
   DateTimeFormatResult,
   NumberFormatResult,
-  Formatter,
   VueI18nOptions,
   VueI18n,
   VueI18nTranslation,
diff --git a/packages/vue-i18n-core/src/legacy.ts b/packages/vue-i18n-core/src/legacy.ts
index 6cb0c559d..d68827ce8 100644
--- a/packages/vue-i18n-core/src/legacy.ts
+++ b/packages/vue-i18n-core/src/legacy.ts
@@ -76,9 +76,6 @@ export type WarnHtmlInMessageLevel = 'off' | 'warn' | 'error'
 export type DateTimeFormatResult = string
 /** @VueI18nLegacy */
 export type NumberFormatResult = string
-export interface Formatter {
-  interpolate(message: string, values: any, path: string): Array<any> | null
-}
 export type VueI18nExtender = (vueI18n: VueI18n) => Disposer | undefined
 
 /**
@@ -181,13 +178,6 @@ export interface VueI18nOptions<
    * @VueI18nSee [Custom Modifiers](../guide/essentials/syntax#custom-modifiers)
    */
   modifiers?: Options['modifiers']
-  /**
-   * @remarks
-   * The formatter that implemented with Formatter interface.
-   *
-   * @deprecated See the [here](../guide/migration/breaking#remove-custom-formatter)
-   */
-  formatter?: Formatter
   /**
    * @remarks
    * A handler for localization missing.
@@ -968,13 +958,6 @@ export interface VueI18n<
    * @VueI18nSee [Custom Modifiers](../guide/essentials/syntax#custom-modifiers)
    */
   readonly modifiers: Composition['modifiers']
-  /**
-   * @remarks
-   * The formatter that implemented with Formatter interface.
-   *
-   * @deprecated See the [here](../guide/migration/breaking#remove-custom-formatter)
-   */
-  formatter: Formatter
   /**
    * @remarks
    * A handler for localization missing.
@@ -1349,10 +1332,6 @@ function convertComposerOptions<
   const escapeParameter = !!options.escapeParameterHtml
   const inheritLocale = isBoolean(options.sync) ? options.sync : true
 
-  if (__DEV__ && options.formatter) {
-    warn(getWarnMessage(I18nWarnCodes.NOT_SUPPORTED_FORMATTER))
-  }
-
   if (__DEV__ && options.preserveDirectiveContent) {
     warn(getWarnMessage(I18nWarnCodes.NOT_SUPPORTED_PRESERVE_DIRECTIVE))
   }
@@ -1512,20 +1491,6 @@ export function createVueI18n(options: any = {}): any {
       return composer.availableLocales as Locale[]
     },
 
-    // formatter
-    get formatter(): Formatter {
-      __DEV__ && warn(getWarnMessage(I18nWarnCodes.NOT_SUPPORTED_FORMATTER))
-      // dummy
-      return {
-        interpolate() {
-          return []
-        }
-      }
-    },
-    set formatter(val: Formatter) {
-      __DEV__ && warn(getWarnMessage(I18nWarnCodes.NOT_SUPPORTED_FORMATTER))
-    },
-
     // missing
     get missing(): MissingHandler | null {
       return composer.getMissingHandler()
diff --git a/packages/vue-i18n-core/src/warnings.ts b/packages/vue-i18n-core/src/warnings.ts
index 1825474d3..e5e345ae2 100644
--- a/packages/vue-i18n-core/src/warnings.ts
+++ b/packages/vue-i18n-core/src/warnings.ts
@@ -7,13 +7,12 @@ const inc = incrementer(code)
 export const I18nWarnCodes = {
   FALLBACK_TO_ROOT: code, // 8
   NOT_SUPPORTED_PRESERVE: inc(), // 9
-  NOT_SUPPORTED_FORMATTER: inc(), // 10
-  NOT_SUPPORTED_PRESERVE_DIRECTIVE: inc(), // 11
-  NOT_SUPPORTED_GET_CHOICE_INDEX: inc(), // 12
-  COMPONENT_NAME_LEGACY_COMPATIBLE: inc(), // 13
-  NOT_FOUND_PARENT_SCOPE: inc(), // 14
-  IGNORE_OBJ_FLATTEN: inc(), // 15
-  NOTICE_DROP_TRANSLATE_EXIST_COMPATIBLE_FLAG: inc() // 16
+  NOT_SUPPORTED_PRESERVE_DIRECTIVE: inc(), // 10
+  NOT_SUPPORTED_GET_CHOICE_INDEX: inc(), // 11
+  COMPONENT_NAME_LEGACY_COMPATIBLE: inc(), // 12
+  NOT_FOUND_PARENT_SCOPE: inc(), // 13
+  IGNORE_OBJ_FLATTEN: inc(), // 14
+  NOTICE_DROP_TRANSLATE_EXIST_COMPATIBLE_FLAG: inc() // 15
 } as const
 
 type I18nWarnCodes = (typeof I18nWarnCodes)[keyof typeof I18nWarnCodes]
@@ -21,7 +20,6 @@ type I18nWarnCodes = (typeof I18nWarnCodes)[keyof typeof I18nWarnCodes]
 export const warnMessages: { [code: number]: string } = {
   [I18nWarnCodes.FALLBACK_TO_ROOT]: `Fall back to {type} '{key}' with root locale.`,
   [I18nWarnCodes.NOT_SUPPORTED_PRESERVE]: `Not supported 'preserve'.`,
-  [I18nWarnCodes.NOT_SUPPORTED_FORMATTER]: `Not supported 'formatter'.`,
   [I18nWarnCodes.NOT_SUPPORTED_PRESERVE_DIRECTIVE]: `Not supported 'preserveDirectiveContent'.`,
   [I18nWarnCodes.NOT_SUPPORTED_GET_CHOICE_INDEX]: `Not supported 'getChoiceIndex'.`,
   [I18nWarnCodes.COMPONENT_NAME_LEGACY_COMPATIBLE]: `Component name legacy compatible: '{name}' -> 'i18n'`,
diff --git a/packages/vue-i18n-core/test/legacy.test.ts b/packages/vue-i18n-core/test/legacy.test.ts
index 6a2c14523..5efc80251 100644
--- a/packages/vue-i18n-core/test/legacy.test.ts
+++ b/packages/vue-i18n-core/test/legacy.test.ts
@@ -57,36 +57,6 @@ test('availableLocales', () => {
   expect(i18n.availableLocales).toEqual(['en', 'ja', 'ru', 'fr'].sort())
 })
 
-test('formatter', () => {
-  const mockWarn = vi.spyOn(shared, 'warn')
-  mockWarn.mockImplementation(() => {})
-
-  const i18n = createVueI18n({
-    formatter: {
-      interpolate() {
-        return []
-      }
-    }
-  })
-
-  expect(i18n.formatter).not.toBeUndefined()
-  i18n.formatter = {
-    interpolate() {
-      return []
-    }
-  }
-  expect(mockWarn).toHaveBeenCalledTimes(3)
-  expect(mockWarn.mock.calls[0][0]).toEqual(
-    getWarnMessage(I18nWarnCodes.NOT_SUPPORTED_FORMATTER)
-  )
-  expect(mockWarn.mock.calls[1][0]).toEqual(
-    getWarnMessage(I18nWarnCodes.NOT_SUPPORTED_FORMATTER)
-  )
-  expect(mockWarn.mock.calls[2][0]).toEqual(
-    getWarnMessage(I18nWarnCodes.NOT_SUPPORTED_FORMATTER)
-  )
-})
-
 test('missing', () => {
   const i18n = createVueI18n()
   expect(i18n.missing).toEqual(null)
diff --git a/packages/vue-i18n/src/index.ts b/packages/vue-i18n/src/index.ts
index 75fab5e18..b54545d20 100644
--- a/packages/vue-i18n/src/index.ts
+++ b/packages/vue-i18n/src/index.ts
@@ -91,7 +91,6 @@ export {
   WarnHtmlInMessageLevel,
   DateTimeFormatResult,
   NumberFormatResult,
-  Formatter,
   VueI18nOptions,
   VueI18n,
   VueI18nTranslation,
diff --git a/packages/vue-i18n/src/runtime.ts b/packages/vue-i18n/src/runtime.ts
index 3c333da3d..c57f6c165 100644
--- a/packages/vue-i18n/src/runtime.ts
+++ b/packages/vue-i18n/src/runtime.ts
@@ -83,7 +83,6 @@ export {
   WarnHtmlInMessageLevel,
   DateTimeFormatResult,
   NumberFormatResult,
-  Formatter,
   VueI18nOptions,
   VueI18n,
   VueI18nTranslation,