diff --git a/packages/kbn-i18n/src/__fixtures__/test_plugin_1/translations/en-US.json b/packages/kbn-i18n/src/__fixtures__/test_plugin_1/translations/en-US.json
index a25da0165b407d..5cd8dd88e36a26 100644
--- a/packages/kbn-i18n/src/__fixtures__/test_plugin_1/translations/en-US.json
+++ b/packages/kbn-i18n/src/__fixtures__/test_plugin_1/translations/en-US.json
@@ -1,4 +1,6 @@
 {
-  "a.b.c": "bar",
-  "d.e.f": "foo"
+  "messages": {
+    "a.b.c": "bar",
+    "d.e.f": "foo"
+  }
 }
diff --git a/packages/kbn-i18n/src/__fixtures__/test_plugin_1/translations/en.json b/packages/kbn-i18n/src/__fixtures__/test_plugin_1/translations/en.json
index eaec1a6d8a0964..36aa3aa450c8f9 100644
--- a/packages/kbn-i18n/src/__fixtures__/test_plugin_1/translations/en.json
+++ b/packages/kbn-i18n/src/__fixtures__/test_plugin_1/translations/en.json
@@ -1,4 +1,6 @@
 {
-  "a.b.c": "foo",
-  "d.e.f": "bar"
+  "messages": {
+    "a.b.c": "foo",
+    "d.e.f": "bar"
+  }
 }
diff --git a/packages/kbn-i18n/src/__fixtures__/test_plugin_2/translations/en.json b/packages/kbn-i18n/src/__fixtures__/test_plugin_2/translations/en.json
index 85a62e3df1a48f..9530a5967eb99b 100644
--- a/packages/kbn-i18n/src/__fixtures__/test_plugin_2/translations/en.json
+++ b/packages/kbn-i18n/src/__fixtures__/test_plugin_2/translations/en.json
@@ -1,4 +1,6 @@
 {
-  "a.b.c.custom": "foo.custom",
-  "d.e.f.custom": "bar.custom"
+  "messages": {
+    "a.b.c.custom": "foo.custom",
+    "d.e.f.custom": "bar.custom"
+  }
 }
diff --git a/packages/kbn-i18n/src/__fixtures__/test_plugin_2/translations/fr.json b/packages/kbn-i18n/src/__fixtures__/test_plugin_2/translations/fr.json
index 04e20542e75e39..88d3f27d9126c8 100644
--- a/packages/kbn-i18n/src/__fixtures__/test_plugin_2/translations/fr.json
+++ b/packages/kbn-i18n/src/__fixtures__/test_plugin_2/translations/fr.json
@@ -1,3 +1,5 @@
 {
-  test: 'test' // JSON5 test
+  messages: {
+    test: 'test' // JSON5 test
+  }
 }
diff --git a/packages/kbn-i18n/src/__fixtures__/test_plugin_2/translations/ru.json b/packages/kbn-i18n/src/__fixtures__/test_plugin_2/translations/ru.json
index d0ae716dbe4c32..e6207873f600ac 100644
--- a/packages/kbn-i18n/src/__fixtures__/test_plugin_2/translations/ru.json
+++ b/packages/kbn-i18n/src/__fixtures__/test_plugin_2/translations/ru.json
@@ -1,3 +1,5 @@
 {
-  "test": "test"
+  "messages": {
+    "test": "test"
+  }
 }
diff --git a/packages/kbn-i18n/src/angular/provider.ts b/packages/kbn-i18n/src/angular/provider.ts
index b239afece4d291..44f0974ac81432 100644
--- a/packages/kbn-i18n/src/angular/provider.ts
+++ b/packages/kbn-i18n/src/angular/provider.ts
@@ -22,8 +22,8 @@ import * as i18n from '../core';
 export type I18nServiceType = ReturnType<I18nProvider['$get']>;
 
 export class I18nProvider implements angular.IServiceProvider {
-  public addMessages = i18n.addMessages;
-  public getMessages = i18n.getMessages;
+  public addTranslation = i18n.addTranslation;
+  public getTranslation = i18n.getTranslation;
   public setLocale = i18n.setLocale;
   public getLocale = i18n.getLocale;
   public setDefaultLocale = i18n.setDefaultLocale;
diff --git a/packages/kbn-i18n/src/core/__snapshots__/i18n.test.ts.snap b/packages/kbn-i18n/src/core/__snapshots__/i18n.test.ts.snap
index 895cd575d3513b..30d4f3f8850536 100644
--- a/packages/kbn-i18n/src/core/__snapshots__/i18n.test.ts.snap
+++ b/packages/kbn-i18n/src/core/__snapshots__/i18n.test.ts.snap
@@ -4,7 +4,7 @@ exports[`I18n engine addMessages should throw error if locale is not specified o
 
 exports[`I18n engine addMessages should throw error if locale is not specified or empty 2`] = `"[I18n] A \`locale\` must be a non-empty string to add messages."`;
 
-exports[`I18n engine addMessages should throw error if locale specified in messages is different from one provided as second argument 1`] = `"[I18n] A \`locale\` in the messages object is different from the one provided as a second argument."`;
+exports[`I18n engine addMessages should throw error if locale specified in messages is different from one provided as second argument 1`] = `"[I18n] A \`locale\` in the translation object is different from the one provided as a second argument."`;
 
 exports[`I18n engine translate should throw error if id is not a non-empty string 1`] = `"[I18n] An \`id\` must be a non-empty string to translate a message."`;
 
diff --git a/packages/kbn-i18n/src/core/i18n.test.ts b/packages/kbn-i18n/src/core/i18n.test.ts
index 24c771aeeecba2..c6c41c9325992a 100644
--- a/packages/kbn-i18n/src/core/i18n.test.ts
+++ b/packages/kbn-i18n/src/core/i18n.test.ts
@@ -33,46 +33,54 @@ describe('I18n engine', () => {
 
   describe('addMessages', () => {
     test('should throw error if locale is not specified or empty', () => {
-      expect(() => i18n.addMessages({ foo: 'bar' })).toThrowErrorMatchingSnapshot();
-      expect(() => i18n.addMessages({ locale: '' })).toThrowErrorMatchingSnapshot();
+      expect(() =>
+        i18n.addTranslation({ messages: { foo: 'bar' } })
+      ).toThrowErrorMatchingSnapshot();
+      expect(() =>
+        i18n.addTranslation({ locale: '', messages: {} })
+      ).toThrowErrorMatchingSnapshot();
     });
 
     test('should throw error if locale specified in messages is different from one provided as second argument', () => {
       expect(() =>
-        i18n.addMessages({ foo: 'bar', locale: 'en' }, 'ru')
+        i18n.addTranslation({ messages: { foo: 'bar' }, locale: 'en' }, 'ru')
       ).toThrowErrorMatchingSnapshot();
     });
 
     test('should add messages if locale prop is passed as second argument', () => {
       const locale = 'ru';
 
-      expect(i18n.getMessages()).toEqual({});
+      expect(i18n.getTranslation()).toEqual({ messages: {} });
 
-      i18n.addMessages({ foo: 'bar' }, locale);
+      i18n.addTranslation({ messages: { foo: 'bar' } }, locale);
 
-      expect(i18n.getMessages()).toEqual({});
+      expect(i18n.getTranslation()).toEqual({ messages: {} });
 
       i18n.setLocale(locale);
 
-      expect(i18n.getMessages()).toEqual({ foo: 'bar' });
+      expect(i18n.getTranslation()).toEqual({ messages: { foo: 'bar' } });
     });
 
     test('should add messages if locale prop is passed as messages property', () => {
       const locale = 'ru';
 
-      expect(i18n.getMessages()).toEqual({});
+      expect(i18n.getTranslation()).toEqual({ messages: {} });
 
-      i18n.addMessages({
+      i18n.addTranslation({
         locale,
-        foo: 'bar',
+        messages: {
+          foo: 'bar',
+        },
       });
 
-      expect(i18n.getMessages()).toEqual({});
+      expect(i18n.getTranslation()).toEqual({ messages: {} });
 
       i18n.setLocale(locale);
 
-      expect(i18n.getMessages()).toEqual({
-        foo: 'bar',
+      expect(i18n.getTranslation()).toEqual({
+        messages: {
+          foo: 'bar',
+        },
         locale: 'ru',
       });
     });
@@ -81,25 +89,33 @@ describe('I18n engine', () => {
       const locale = 'ru';
 
       i18n.setLocale(locale);
-      i18n.addMessages({
+      i18n.addTranslation({
         locale,
-        ['a.b.c']: 'foo',
+        messages: {
+          ['a.b.c']: 'foo',
+        },
       });
 
-      expect(i18n.getMessages()).toEqual({
+      expect(i18n.getTranslation()).toEqual({
         locale: 'ru',
-        ['a.b.c']: 'foo',
+        messages: {
+          ['a.b.c']: 'foo',
+        },
       });
 
-      i18n.addMessages({
+      i18n.addTranslation({
         locale,
-        ['d.e.f']: 'bar',
+        messages: {
+          ['d.e.f']: 'bar',
+        },
       });
 
-      expect(i18n.getMessages()).toEqual({
+      expect(i18n.getTranslation()).toEqual({
         locale: 'ru',
-        ['a.b.c']: 'foo',
-        ['d.e.f']: 'bar',
+        messages: {
+          ['a.b.c']: 'foo',
+          ['d.e.f']: 'bar',
+        },
       });
     });
 
@@ -107,24 +123,32 @@ describe('I18n engine', () => {
       const locale = 'ru';
 
       i18n.setLocale(locale);
-      i18n.addMessages({
+      i18n.addTranslation({
         locale,
-        ['a.b.c']: 'foo',
+        messages: {
+          ['a.b.c']: 'foo',
+        },
       });
 
-      expect(i18n.getMessages()).toEqual({
+      expect(i18n.getTranslation()).toEqual({
         locale: 'ru',
-        ['a.b.c']: 'foo',
+        messages: {
+          ['a.b.c']: 'foo',
+        },
       });
 
-      i18n.addMessages({
+      i18n.addTranslation({
         locale,
-        ['a.b.c']: 'bar',
+        messages: {
+          ['a.b.c']: 'bar',
+        },
       });
 
-      expect(i18n.getMessages()).toEqual({
+      expect(i18n.getTranslation()).toEqual({
         locale: 'ru',
-        ['a.b.c']: 'bar',
+        messages: {
+          ['a.b.c']: 'bar',
+        },
       });
     });
 
@@ -132,52 +156,64 @@ describe('I18n engine', () => {
       const locale = 'en-us';
       i18n.setLocale(locale);
 
-      i18n.addMessages(
+      i18n.addTranslation(
         {
-          ['a.b.c']: 'bar',
+          messages: {
+            ['a.b.c']: 'bar',
+          },
         },
         'en_US'
       );
 
       expect(i18n.getLocale()).toBe(locale);
-      expect(i18n.getMessages()).toEqual({
-        ['a.b.c']: 'bar',
+      expect(i18n.getTranslation()).toEqual({
+        messages: {
+          ['a.b.c']: 'bar',
+        },
       });
     });
   });
 
-  describe('getMessages', () => {
+  describe('getTranslation', () => {
     test('should return messages for the current language', () => {
-      i18n.addMessages({
+      i18n.addTranslation({
         locale: 'ru',
-        foo: 'bar',
+        messages: {
+          foo: 'bar',
+        },
       });
-      i18n.addMessages({
+      i18n.addTranslation({
         locale: 'en',
-        bar: 'foo',
+        messages: {
+          bar: 'foo',
+        },
       });
 
       i18n.setLocale('ru');
-      expect(i18n.getMessages()).toEqual({
+      expect(i18n.getTranslation()).toEqual({
         locale: 'ru',
-        foo: 'bar',
+        messages: {
+          foo: 'bar',
+        },
       });
 
       i18n.setLocale('en');
-      expect(i18n.getMessages()).toEqual({
+      expect(i18n.getTranslation()).toEqual({
         locale: 'en',
-        bar: 'foo',
+        messages: {
+          bar: 'foo',
+        },
       });
     });
 
     test('should return an empty object if messages for current locale are not specified', () => {
-      expect(i18n.getMessages()).toEqual({});
+      expect(i18n.getTranslation()).toEqual({ messages: {} });
 
       i18n.setLocale('fr');
-      expect(i18n.getMessages()).toEqual({});
+      expect(i18n.getTranslation()).toEqual({ messages: {} });
 
       i18n.setLocale('en');
-      expect(i18n.getMessages()).toEqual({});
+      expect(i18n.getTranslation()).toEqual({ messages: {} });
     });
   });
 
@@ -352,22 +388,25 @@ describe('I18n engine', () => {
     });
 
     test('should return array of registered locales', () => {
-      i18n.addMessages({
+      i18n.addTranslation({
         locale: 'en',
+        messages: {},
       });
 
       expect(i18n.getRegisteredLocales()).toEqual(['en']);
 
-      i18n.addMessages({
+      i18n.addTranslation({
         locale: 'ru',
+        messages: {},
       });
 
       expect(i18n.getRegisteredLocales()).toContain('en');
       expect(i18n.getRegisteredLocales()).toContain('ru');
       expect(i18n.getRegisteredLocales().length).toBe(2);
 
-      i18n.addMessages({
+      i18n.addTranslation({
         locale: 'fr',
+        messages: {},
       });
 
       expect(i18n.getRegisteredLocales()).toContain('en');
@@ -394,7 +433,9 @@ describe('I18n engine', () => {
     test('should return message as is if values are not provided', () => {
       i18n.init({
         locale: 'en',
-        ['a.b.c']: 'foo',
+        messages: {
+          ['a.b.c']: 'foo',
+        },
       });
 
       expect(i18n.translate('a.b.c')).toBe('foo');
@@ -407,7 +448,9 @@ describe('I18n engine', () => {
     test('should not return defaultMessage as is if values are provided', () => {
       i18n.init({
         locale: 'en',
-        ['a.b.c']: 'foo',
+        messages: {
+          ['a.b.c']: 'foo',
+        },
       });
       expect(i18n.translate('a.b.c', { defaultMessage: 'bar' })).toBe('foo');
     });
@@ -415,8 +458,10 @@ describe('I18n engine', () => {
     test('should interpolate variables', () => {
       i18n.init({
         locale: 'en',
-        ['a.b.c']: 'foo {a}, {b}, {c} bar',
-        ['d.e.f']: '{foo}',
+        messages: {
+          ['a.b.c']: 'foo {a}, {b}, {c} bar',
+          ['d.e.f']: '{foo}',
+        },
       });
 
       expect(
@@ -440,11 +485,13 @@ describe('I18n engine', () => {
     test('should format pluralized messages', () => {
       i18n.init({
         locale: 'en',
-        ['a.b.c']: `You have {numPhotos, plural,
+        messages: {
+          ['a.b.c']: `You have {numPhotos, plural,
                       =0 {no photos.}
                       =1 {one photo.}
                       other {# photos.}
                    }`,
+        },
       });
 
       expect(i18n.translate('a.b.c', { values: { numPhotos: 0 } })).toBe('You have no photos.');
@@ -494,11 +541,13 @@ describe('I18n engine', () => {
     test('should throw error if wrong context is provided to the translation string', () => {
       i18n.init({
         locale: 'en',
-        ['a.b.c']: `You have {numPhotos, plural,
+        messages: {
+          ['a.b.c']: `You have {numPhotos, plural,
                       =0 {no photos.}
                       =1 {one photo.}
                       other {# photos.}
                    }`,
+        },
       });
       i18n.setDefaultLocale('en');
 
@@ -519,7 +568,9 @@ describe('I18n engine', () => {
     test('should format messages with percent formatter', () => {
       i18n.init({
         locale: 'en',
-        ['a.b.c']: 'Result: {result, number, percent}',
+        messages: {
+          ['a.b.c']: 'Result: {result, number, percent}',
+        },
       });
       i18n.setDefaultLocale('en');
 
@@ -536,10 +587,12 @@ describe('I18n engine', () => {
     test('should format messages with date formatter', () => {
       i18n.init({
         locale: 'en',
-        ['a.short']: 'Sale begins {start, date, short}',
-        ['a.medium']: 'Sale begins {start, date, medium}',
-        ['a.long']: 'Sale begins {start, date, long}',
-        ['a.full']: 'Sale begins {start, date, full}',
+        messages: {
+          ['a.short']: 'Sale begins {start, date, short}',
+          ['a.medium']: 'Sale begins {start, date, medium}',
+          ['a.long']: 'Sale begins {start, date, long}',
+          ['a.full']: 'Sale begins {start, date, full}',
+        },
       });
 
       expect(
@@ -602,8 +655,10 @@ describe('I18n engine', () => {
     test('should format messages with time formatter', () => {
       i18n.init({
         locale: 'en',
-        ['a.short']: 'Coupon expires at {expires, time, short}',
-        ['a.medium']: 'Coupon expires at {expires, time, medium}',
+        messages: {
+          ['a.short']: 'Coupon expires at {expires, time, short}',
+          ['a.medium']: 'Coupon expires at {expires, time, medium}',
+        },
       });
 
       expect(
@@ -645,8 +700,10 @@ describe('I18n engine', () => {
             usd: { style: 'currency', currency: 'USD' },
           },
         },
-        ['a.b.c']: 'Your total is {total, number, usd}',
-        ['d.e.f']: 'Your total is {total, number, eur}',
+        messages: {
+          ['a.b.c']: 'Your total is {total, number, usd}',
+          ['d.e.f']: 'Your total is {total, number, eur}',
+        },
       });
 
       expect(i18n.translate('a.b.c', { values: { total: 1000 } })).toBe('Your total is $1,000.00');
@@ -670,6 +727,7 @@ describe('I18n engine', () => {
             usd: { style: 'currency', currency: 'USD' },
           },
         },
+        messages: {},
       });
       i18n.setDefaultLocale('en');
 
@@ -704,7 +762,9 @@ describe('I18n engine', () => {
     test('should use default format if passed format option is not specified', () => {
       i18n.init({
         locale: 'en',
-        ['a.b.c']: 'Your total is {total, number, usd}',
+        messages: {
+          ['a.b.c']: 'Your total is {total, number, usd}',
+        },
       });
       i18n.setDefaultLocale('en');
 
@@ -721,7 +781,9 @@ describe('I18n engine', () => {
     test('should throw error if used format is not specified', () => {
       i18n.init({
         locale: 'en',
-        ['a.b.c']: 'Your total is {total, foo}',
+        messages: {
+          ['a.b.c']: 'Your total is {total, foo}',
+        },
       });
       i18n.setDefaultLocale('en');
 
@@ -741,28 +803,32 @@ describe('I18n engine', () => {
   describe('init', () => {
     test('should not initialize the engine if messages are not specified', () => {
       i18n.init();
-      expect(i18n.getMessages()).toEqual({});
+      expect(i18n.getTranslation()).toEqual({ messages: {} });
     });
 
     test('should throw error if messages are empty', () => {
-      expect(() => i18n.init({})).toThrow();
-      expect(i18n.getMessages()).toEqual({});
+      expect(() => i18n.init({ messages: {} })).toThrow();
+      expect(i18n.getTranslation()).toEqual({ messages: {} });
     });
 
     test('should add messages if locale is specified', () => {
       i18n.init({
         locale: 'en',
-        foo: 'bar',
+        messages: {
+          foo: 'bar',
+        },
       });
 
-      expect(i18n.getMessages()).toEqual({
+      expect(i18n.getTranslation()).toEqual({
         locale: 'en',
-        foo: 'bar',
+        messages: {
+          foo: 'bar',
+        },
       });
     });
 
     test('should set the current locale', () => {
-      i18n.init({ locale: 'ru' });
+      i18n.init({ locale: 'ru', messages: {} });
       expect(i18n.getLocale()).toBe('ru');
     });
 
@@ -778,6 +844,7 @@ describe('I18n engine', () => {
             },
           },
         },
+        messages: {},
       });
 
       expect((i18n.getFormats().date as any).custom).toEqual({
diff --git a/packages/kbn-i18n/src/core/i18n.ts b/packages/kbn-i18n/src/core/i18n.ts
index 027c3411d0ed63..beae2a486130d3 100644
--- a/packages/kbn-i18n/src/core/i18n.ts
+++ b/packages/kbn-i18n/src/core/i18n.ts
@@ -21,7 +21,7 @@ import memoizeIntlConstructor from 'intl-format-cache';
 import IntlMessageFormat from 'intl-messageformat';
 import IntlRelativeFormat from 'intl-relativeformat';
 
-import { Messages, PlainMessages } from '../messages';
+import { Translation } from '../translation';
 import { Formats, formats as EN_FORMATS } from './formats';
 import { hasValues, isObject, isString, mergeAll } from './helper';
 import { isPseudoLocale, translateUsingPseudoLocale } from './pseudo_locale';
@@ -31,7 +31,7 @@ import './locales.js';
 
 const EN_LOCALE = 'en';
 const LOCALE_DELIMITER = '-';
-const messages: Messages = {};
+const translationsForLocale: Record<string, Translation> = {};
 const getMessageFormat = memoizeIntlConstructor(IntlMessageFormat);
 
 let defaultLocale = EN_LOCALE;
@@ -45,8 +45,9 @@ IntlRelativeFormat.defaultLocale = defaultLocale;
  * Returns message by the given message id.
  * @param id - path to the message
  */
-function getMessageById(id: string): string {
-  return getMessages()[id];
+function getMessageById(id: string): string | undefined {
+  const translation = getTranslation();
+  return translation.messages ? translation.messages[id] : undefined;
 }
 
 /**
@@ -59,33 +60,38 @@ function normalizeLocale(locale: string) {
 
 /**
  * Provides a way to register translations with the engine
- * @param newMessages
+ * @param newTranslation
  * @param [locale = messages.locale]
  */
-export function addMessages(newMessages: PlainMessages = {}, locale = newMessages.locale) {
+export function addTranslation(newTranslation: Translation, locale = newTranslation.locale) {
   if (!locale || !isString(locale)) {
     throw new Error('[I18n] A `locale` must be a non-empty string to add messages.');
   }
 
-  if (newMessages.locale && newMessages.locale !== locale) {
+  if (newTranslation.locale && newTranslation.locale !== locale) {
     throw new Error(
-      '[I18n] A `locale` in the messages object is different from the one provided as a second argument.'
+      '[I18n] A `locale` in the translation object is different from the one provided as a second argument.'
     );
   }
 
   const normalizedLocale = normalizeLocale(locale);
-
-  messages[normalizedLocale] = {
-    ...messages[normalizedLocale],
-    ...newMessages,
+  const existingTranslation = translationsForLocale[normalizedLocale] || { messages: {} };
+
+  translationsForLocale[normalizedLocale] = {
+    formats: newTranslation.formats || existingTranslation.formats,
+    locale: newTranslation.locale || existingTranslation.locale,
+    messages: {
+      ...existingTranslation.messages,
+      ...newTranslation.messages,
+    },
   };
 }
 
 /**
  * Returns messages for the current language
  */
-export function getMessages(): PlainMessages {
-  return messages[currentLocale] || {};
+export function getTranslation(): Translation {
+  return translationsForLocale[currentLocale] || { messages: {} };
 }
 
 /**
@@ -155,7 +161,7 @@ export function getFormats() {
  * Returns array of locales having translations
  */
 export function getRegisteredLocales() {
-  return Object.keys(messages);
+  return Object.keys(translationsForLocale);
 }
 
 interface TranslateArguments {
@@ -218,20 +224,20 @@ export function translate(
 
 /**
  * Initializes the engine
- * @param newMessages
+ * @param newTranslation
  */
-export function init(newMessages?: PlainMessages) {
-  if (!newMessages) {
+export function init(newTranslation?: Translation) {
+  if (!newTranslation) {
     return;
   }
 
-  addMessages(newMessages);
+  addTranslation(newTranslation);
 
-  if (newMessages.locale) {
-    setLocale(newMessages.locale);
+  if (newTranslation.locale) {
+    setLocale(newTranslation.locale);
   }
 
-  if (newMessages.formats) {
-    setFormats(newMessages.formats);
+  if (newTranslation.formats) {
+    setFormats(newTranslation.formats);
   }
 }
diff --git a/packages/kbn-i18n/src/loader.test.ts b/packages/kbn-i18n/src/loader.test.ts
index df99c22ede71b2..72cfeb09974ac9 100644
--- a/packages/kbn-i18n/src/loader.test.ts
+++ b/packages/kbn-i18n/src/loader.test.ts
@@ -100,8 +100,10 @@ describe('I18n loader', () => {
 
       expect(await i18nLoader.getTranslationsByLocale('en')).toEqual({
         locale: 'en',
-        ['a.b.c']: 'foo',
-        ['d.e.f']: 'bar',
+        messages: {
+          ['a.b.c']: 'foo',
+          ['d.e.f']: 'bar',
+        },
       });
     });
 
@@ -110,7 +112,7 @@ describe('I18n loader', () => {
         join(__dirname, './__fixtures__/test_plugin_1/translations/en.json')
       );
 
-      expect(await i18nLoader.getTranslationsByLocale('ru')).toEqual({});
+      expect(await i18nLoader.getTranslationsByLocale('ru')).toEqual({ messages: {} });
     });
 
     test('should return translation messages from a couple of files by specified locale', async () => {
@@ -121,10 +123,12 @@ describe('I18n loader', () => {
 
       expect(await i18nLoader.getTranslationsByLocale('en')).toEqual({
         locale: 'en',
-        ['a.b.c']: 'foo',
-        ['d.e.f']: 'bar',
-        ['a.b.c.custom']: 'foo.custom',
-        ['d.e.f.custom']: 'bar.custom',
+        messages: {
+          ['a.b.c']: 'foo',
+          ['d.e.f']: 'bar',
+          ['a.b.c.custom']: 'foo.custom',
+          ['d.e.f.custom']: 'bar.custom',
+        },
       });
     });
 
@@ -138,21 +142,27 @@ describe('I18n loader', () => {
 
       expect(await i18nLoader.getTranslationsByLocale('en')).toEqual({
         locale: 'en',
-        ['a.b.c']: 'foo',
-        ['d.e.f']: 'bar',
-        ['a.b.c.custom']: 'foo.custom',
-        ['d.e.f.custom']: 'bar.custom',
+        messages: {
+          ['a.b.c']: 'foo',
+          ['d.e.f']: 'bar',
+          ['a.b.c.custom']: 'foo.custom',
+          ['d.e.f.custom']: 'bar.custom',
+        },
       });
 
       expect(await i18nLoader.getTranslationsByLocale('en-US')).toEqual({
         locale: 'en-US',
-        ['a.b.c']: 'bar',
-        ['d.e.f']: 'foo',
+        messages: {
+          ['a.b.c']: 'bar',
+          ['d.e.f']: 'foo',
+        },
       });
 
       expect(await i18nLoader.getTranslationsByLocale('ru')).toEqual({
         locale: 'ru',
-        test: 'test',
+        messages: {
+          test: 'test',
+        },
       });
     });
 
@@ -163,7 +173,9 @@ describe('I18n loader', () => {
 
       expect(await i18nLoader.getTranslationsByLocale('fr')).toEqual({
         locale: 'fr',
-        test: 'test',
+        messages: {
+          test: 'test',
+        },
       });
     });
   });
@@ -180,19 +192,25 @@ describe('I18n loader', () => {
       expect(await i18nLoader.getAllTranslations()).toEqual({
         en: {
           locale: 'en',
-          ['a.b.c']: 'foo',
-          ['d.e.f']: 'bar',
-          ['a.b.c.custom']: 'foo.custom',
-          ['d.e.f.custom']: 'bar.custom',
+          messages: {
+            ['a.b.c']: 'foo',
+            ['d.e.f']: 'bar',
+            ['a.b.c.custom']: 'foo.custom',
+            ['d.e.f.custom']: 'bar.custom',
+          },
         },
         ['en-US']: {
           locale: 'en-US',
-          ['a.b.c']: 'bar',
-          ['d.e.f']: 'foo',
+          messages: {
+            ['a.b.c']: 'bar',
+            ['d.e.f']: 'foo',
+          },
         },
         ru: {
           locale: 'ru',
-          test: 'test',
+          messages: {
+            test: 'test',
+          },
         },
       });
     });
@@ -214,19 +232,25 @@ describe('I18n loader', () => {
       ).toEqual({
         en: {
           locale: 'en',
-          ['a.b.c']: 'foo',
-          ['d.e.f']: 'bar',
-          ['a.b.c.custom']: 'foo.custom',
-          ['d.e.f.custom']: 'bar.custom',
+          messages: {
+            ['a.b.c']: 'foo',
+            ['d.e.f']: 'bar',
+            ['a.b.c.custom']: 'foo.custom',
+            ['d.e.f.custom']: 'bar.custom',
+          },
         },
         ['en-US']: {
           locale: 'en-US',
-          ['a.b.c']: 'bar',
-          ['d.e.f']: 'foo',
+          messages: {
+            ['a.b.c']: 'bar',
+            ['d.e.f']: 'foo',
+          },
         },
         ru: {
           locale: 'ru',
-          test: 'test',
+          messages: {
+            test: 'test',
+          },
         },
       });
     });
diff --git a/packages/kbn-i18n/src/loader.ts b/packages/kbn-i18n/src/loader.ts
index e45964b94e3f97..6efafc18ae79bf 100644
--- a/packages/kbn-i18n/src/loader.ts
+++ b/packages/kbn-i18n/src/loader.ts
@@ -23,7 +23,7 @@ import * as path from 'path';
 import { promisify } from 'util';
 
 import { unique } from './core/helper';
-import { Messages, PlainMessages } from './messages';
+import { Translation } from './translation';
 
 const asyncReadFile = promisify(readFile);
 
@@ -39,7 +39,7 @@ const translationsRegistry: { [key: string]: string[] } = {};
  * Internal property for caching loaded translations files.
  * Key is path to translation file, value is object with translation messages
  */
-const loadedFiles: { [key: string]: PlainMessages } = {};
+const loadedFiles: { [key: string]: Translation } = {};
 
 /**
  * Returns locale by the given translation file name
@@ -69,7 +69,7 @@ function getLocaleFromFileName(fullFileName: string) {
  * @param pathToFile
  * @returns
  */
-async function loadFile(pathToFile: string): Promise<PlainMessages> {
+async function loadFile(pathToFile: string): Promise<Translation> {
   return JSON5.parse(await asyncReadFile(pathToFile, 'utf8'));
 }
 
@@ -127,7 +127,7 @@ export function getRegisteredLocales() {
  * @param locale
  * @returns translation messages
  */
-export async function getTranslationsByLocale(locale: string): Promise<PlainMessages> {
+export async function getTranslationsByLocale(locale: string): Promise<Translation> {
   const files = translationsRegistry[locale] || [];
   const notLoadedFiles = files.filter(file => !loadedFiles[file]);
 
@@ -135,15 +135,21 @@ export async function getTranslationsByLocale(locale: string): Promise<PlainMess
     await loadAndCacheFiles(notLoadedFiles);
   }
 
-  return files.length
-    ? files.reduce(
-        (messages, file) => ({
-          ...messages,
-          ...loadedFiles[file],
-        }),
-        { locale }
-      )
-    : {};
+  if (!files.length) {
+    return { messages: {} };
+  }
+
+  return files.reduce(
+    (translation: Translation, file) => ({
+      locale: loadedFiles[file].locale || translation.locale,
+      formats: loadedFiles[file].formats || translation.formats,
+      messages: {
+        ...loadedFiles[file].messages,
+        ...translation.messages,
+      },
+    }),
+    { locale, messages: {} }
+  );
 }
 
 /**
@@ -151,7 +157,7 @@ export async function getTranslationsByLocale(locale: string): Promise<PlainMess
  * @returns A Promise object
  * where keys are the locale and values are objects of translation messages
  */
-export async function getAllTranslations(): Promise<{ [key: string]: Messages }> {
+export async function getAllTranslations(): Promise<{ [key: string]: Translation }> {
   const locales = getRegisteredLocales();
   const translations = await Promise.all(locales.map(getTranslationsByLocale));
 
diff --git a/packages/kbn-i18n/src/react/__snapshots__/inject_i18n_provider.test.tsx.snap b/packages/kbn-i18n/src/react/__snapshots__/inject_i18n_provider.test.tsx.snap
index df3ea6450d0be8..7ad7a6fbc1f00c 100644
--- a/packages/kbn-i18n/src/react/__snapshots__/inject_i18n_provider.test.tsx.snap
+++ b/packages/kbn-i18n/src/react/__snapshots__/inject_i18n_provider.test.tsx.snap
@@ -66,62 +66,7 @@ Object {
   "formatPlural": [Function],
   "formatRelative": [Function],
   "formatTime": [Function],
-  "formats": Object {
-    "date": Object {
-      "full": Object {
-        "day": "numeric",
-        "month": "long",
-        "weekday": "long",
-        "year": "numeric",
-      },
-      "long": Object {
-        "day": "numeric",
-        "month": "long",
-        "year": "numeric",
-      },
-      "medium": Object {
-        "day": "numeric",
-        "month": "short",
-        "year": "numeric",
-      },
-      "short": Object {
-        "day": "numeric",
-        "month": "numeric",
-        "year": "2-digit",
-      },
-    },
-    "number": Object {
-      "currency": Object {
-        "style": "currency",
-      },
-      "percent": Object {
-        "style": "percent",
-      },
-    },
-    "time": Object {
-      "full": Object {
-        "hour": "numeric",
-        "minute": "numeric",
-        "second": "numeric",
-        "timeZoneName": "short",
-      },
-      "long": Object {
-        "hour": "numeric",
-        "minute": "numeric",
-        "second": "numeric",
-        "timeZoneName": "short",
-      },
-      "medium": Object {
-        "hour": "numeric",
-        "minute": "numeric",
-        "second": "numeric",
-      },
-      "short": Object {
-        "hour": "numeric",
-        "minute": "numeric",
-      },
-    },
-  },
+  "formats": Object {},
   "formatters": Object {
     "getDateTimeFormat": [Function],
     "getMessageFormat": [Function],
diff --git a/packages/kbn-i18n/src/react/__snapshots__/provider.test.tsx.snap b/packages/kbn-i18n/src/react/__snapshots__/provider.test.tsx.snap
index 0ce4cf1a774768..67701d6c14697d 100644
--- a/packages/kbn-i18n/src/react/__snapshots__/provider.test.tsx.snap
+++ b/packages/kbn-i18n/src/react/__snapshots__/provider.test.tsx.snap
@@ -66,62 +66,7 @@ Object {
   "formatPlural": [Function],
   "formatRelative": [Function],
   "formatTime": [Function],
-  "formats": Object {
-    "date": Object {
-      "full": Object {
-        "day": "numeric",
-        "month": "long",
-        "weekday": "long",
-        "year": "numeric",
-      },
-      "long": Object {
-        "day": "numeric",
-        "month": "long",
-        "year": "numeric",
-      },
-      "medium": Object {
-        "day": "numeric",
-        "month": "short",
-        "year": "numeric",
-      },
-      "short": Object {
-        "day": "numeric",
-        "month": "numeric",
-        "year": "2-digit",
-      },
-    },
-    "number": Object {
-      "currency": Object {
-        "style": "currency",
-      },
-      "percent": Object {
-        "style": "percent",
-      },
-    },
-    "time": Object {
-      "full": Object {
-        "hour": "numeric",
-        "minute": "numeric",
-        "second": "numeric",
-        "timeZoneName": "short",
-      },
-      "long": Object {
-        "hour": "numeric",
-        "minute": "numeric",
-        "second": "numeric",
-        "timeZoneName": "short",
-      },
-      "medium": Object {
-        "hour": "numeric",
-        "minute": "numeric",
-        "second": "numeric",
-      },
-      "short": Object {
-        "hour": "numeric",
-        "minute": "numeric",
-      },
-    },
-  },
+  "formats": Object {},
   "formatters": Object {
     "getDateTimeFormat": [Function],
     "getMessageFormat": [Function],
diff --git a/packages/kbn-i18n/src/react/provider.tsx b/packages/kbn-i18n/src/react/provider.tsx
index b1468ff8733fce..42718fd689ac33 100644
--- a/packages/kbn-i18n/src/react/provider.tsx
+++ b/packages/kbn-i18n/src/react/provider.tsx
@@ -58,9 +58,9 @@ export class I18nProvider extends React.PureComponent {
     return (
       <IntlProvider
         locale={i18n.getLocale()}
-        messages={i18n.getMessages()}
+        messages={i18n.getTranslation().messages}
         defaultLocale={i18n.getDefaultLocale()}
-        formats={i18n.getFormats()}
+        formats={i18n.getTranslation().formats}
         defaultFormats={i18n.getFormats()}
         textComponent={React.Fragment}
       >
diff --git a/packages/kbn-i18n/src/messages.ts b/packages/kbn-i18n/src/translation.ts
similarity index 78%
rename from packages/kbn-i18n/src/messages.ts
rename to packages/kbn-i18n/src/translation.ts
index edfea322c7436a..20a27ca72a72c3 100644
--- a/packages/kbn-i18n/src/messages.ts
+++ b/packages/kbn-i18n/src/translation.ts
@@ -19,21 +19,17 @@
 
 import { Formats } from './core/formats';
 
-/**
- * Messages tree, where leafs are translated strings
- */
-export interface Messages {
-  [key: string]: PlainMessages;
-}
-
-export interface PlainMessages {
-  [key: string]: any;
+export interface Translation {
+  /**
+   * Actual translated messages.
+   */
+  messages: Record<string, string>;
   /**
-   * locale of the messages
+   * Locale of the translated messages.
    */
   locale?: string;
   /**
-   * set of options to the underlying formatter
+   * Set of options to the underlying formatter.
    */
   formats?: Formats;
 }
diff --git a/src/dev/i18n/serializers/__snapshots__/json.test.js.snap b/src/dev/i18n/serializers/__snapshots__/json.test.js.snap
index c35e91e25cbb68..decfeb17c05683 100644
--- a/src/dev/i18n/serializers/__snapshots__/json.test.js.snap
+++ b/src/dev/i18n/serializers/__snapshots__/json.test.js.snap
@@ -58,10 +58,12 @@ exports[`dev/i18n/serializers/json should serialize default messages to JSON 1`]
       }
     }
   },
-  \\"plugin1.message.id-1\\": \\"Message text 1 \\",
-  \\"plugin2.message.id-2\\": {
-    \\"text\\": \\"Message text 2\\",
-    \\"comment\\": \\"Message context\\"
+  \\"messages\\": {
+    \\"plugin1.message.id-1\\": \\"Message text 1 \\",
+    \\"plugin2.message.id-2\\": {
+      \\"text\\": \\"Message text 2\\",
+      \\"comment\\": \\"Message context\\"
+    }
   }
 }"
 `;
diff --git a/src/dev/i18n/serializers/__snapshots__/json5.test.js.snap b/src/dev/i18n/serializers/__snapshots__/json5.test.js.snap
index 2166b32f28fd16..d643661ce58a5e 100644
--- a/src/dev/i18n/serializers/__snapshots__/json5.test.js.snap
+++ b/src/dev/i18n/serializers/__snapshots__/json5.test.js.snap
@@ -58,8 +58,10 @@ exports[`dev/i18n/serializers/json5 should serialize default messages to JSON5 1
       },
     },
   },
-  'plugin1.message.id-1': 'Message text 1',
-  'plugin2.message.id-2': 'Message text 2', // Message context
+  messages: {
+    'plugin1.message.id-1': 'Message text 1',
+    'plugin2.message.id-2': 'Message text 2', // Message context
+  },
 }
 "
 `;
diff --git a/src/dev/i18n/serializers/json.js b/src/dev/i18n/serializers/json.js
index 8e615af1e81d32..149bb0236a63eb 100644
--- a/src/dev/i18n/serializers/json.js
+++ b/src/dev/i18n/serializers/json.js
@@ -20,13 +20,13 @@
 import { i18n } from '@kbn/i18n';
 
 export function serializeToJson(defaultMessages) {
-  const resultJsonObject = { formats: i18n.formats };
+  const resultJsonObject = { formats: i18n.formats, messages: {} };
 
   for (const [mapKey, mapValue] of defaultMessages) {
     if (mapValue.context) {
-      resultJsonObject[mapKey] = { text: mapValue.message, comment: mapValue.context };
+      resultJsonObject.messages[mapKey] = { text: mapValue.message, comment: mapValue.context };
     } else {
-      resultJsonObject[mapKey] = mapValue.message;
+      resultJsonObject.messages[mapKey] = mapValue.message;
     }
   }
 
diff --git a/src/dev/i18n/serializers/json5.js b/src/dev/i18n/serializers/json5.js
index 0156053d5f43b5..9b2c013df7724d 100644
--- a/src/dev/i18n/serializers/json5.js
+++ b/src/dev/i18n/serializers/json5.js
@@ -23,9 +23,11 @@ import { i18n } from '@kbn/i18n';
 const ESCAPE_SINGLE_QUOTE_REGEX = /\\([\s\S])|(')/g;
 
 export function serializeToJson5(defaultMessages) {
-  // .slice(0, -1): remove closing curly brace from json to append messages
+  // .slice(0, -4): remove closing curly braces from json to append messages
   let jsonBuffer = Buffer.from(
-    JSON5.stringify({ formats: i18n.formats }, { quote: `'`, space: 2 }).slice(0, -1)
+    JSON5.stringify({ formats: i18n.formats, messages: {} }, { quote: `'`, space: 2 })
+      .slice(0, -4)
+      .concat('\n')
   );
 
   for (const [mapKey, mapValue] of defaultMessages) {
@@ -36,13 +38,13 @@ export function serializeToJson5(defaultMessages) {
 
     jsonBuffer = Buffer.concat([
       jsonBuffer,
-      Buffer.from(`  '${mapKey}': '${formattedMessage}',`),
+      Buffer.from(`    '${mapKey}': '${formattedMessage}',`),
       Buffer.from(formattedContext ? ` // ${formattedContext}\n` : '\n'),
     ]);
   }
 
-  // append previously removed closing curly brace
-  jsonBuffer = Buffer.concat([jsonBuffer, Buffer.from('}\n')]);
+  // append previously removed closing curly braces
+  jsonBuffer = Buffer.concat([jsonBuffer, Buffer.from('  },\n}\n')]);
 
   return jsonBuffer;
 }