diff --git a/packages/theme/api-report.md b/packages/theme/api-report.md
index 863ab81b68..c61245e0e2 100644
--- a/packages/theme/api-report.md
+++ b/packages/theme/api-report.md
@@ -9,7 +9,7 @@ import { PaletteOptions } from '@material-ui/core/styles/createPalette';
 import { Theme } from '@material-ui/core';
 import { ThemeOptions } from '@material-ui/core';
 
-// @public
+// @public @deprecated
 export type BackstagePalette = Palette & BackstagePaletteAdditions;
 
 // @public
@@ -75,11 +75,11 @@ export type BackstagePaletteAdditions = {
   };
 };
 
-// @public
+// @public @deprecated
 export type BackstagePaletteOptions = PaletteOptions &
   BackstagePaletteAdditions;
 
-// @public
+// @public @deprecated
 export interface BackstageTheme extends Theme {
   // (undocumented)
   getPageTheme: (selector: PageThemeSelector) => PageTheme;
@@ -89,7 +89,7 @@ export interface BackstageTheme extends Theme {
   palette: BackstagePalette;
 }
 
-// @public
+// @public @deprecated
 export interface BackstageThemeOptions extends ThemeOptions {
   // (undocumented)
   getPageTheme: (selector: PageThemeSelector) => PageTheme;
@@ -102,19 +102,28 @@ export interface BackstageThemeOptions extends ThemeOptions {
 // @public
 export const colorVariants: Record<string, string[]>;
 
-// @public
-export function createTheme(options: SimpleThemeOptions): BackstageTheme;
+// @public @deprecated (undocumented)
+export const createTheme: typeof createV4Theme;
+
+// @public @deprecated (undocumented)
+export const createThemeOptions: typeof createV4ThemeOptions;
+
+// @public @deprecated (undocumented)
+export const createThemeOverrides: typeof createV4ThemeOverrides;
 
 // @public
-export function createThemeOptions(
-  options: SimpleThemeOptions,
-): BackstageThemeOptions;
+export function createV4Theme(options: SimpleV4ThemeOptions): Theme;
 
 // @public
-export function createThemeOverrides(theme: BackstageTheme): Overrides;
+export function createV4ThemeOptions(
+  options: SimpleV4ThemeOptions,
+): ThemeOptions;
 
 // @public
-export const darkTheme: BackstageTheme;
+export function createV4ThemeOverrides(theme: Theme): Overrides;
+
+// @public
+export const darkTheme: Theme;
 
 // @public
 export function genPageTheme(props: {
@@ -126,7 +135,7 @@ export function genPageTheme(props: {
 }): PageTheme;
 
 // @public
-export const lightTheme: BackstageTheme;
+export const lightTheme: Theme;
 
 // @public
 export type PageTheme = {
@@ -147,9 +156,12 @@ export type PageThemeSelector = {
 // @public
 export const shapes: Record<string, string>;
 
+// @public @deprecated (undocumented)
+export type SimpleThemeOptions = SimpleV4ThemeOptions;
+
 // @public
-export type SimpleThemeOptions = {
-  palette: BackstagePaletteOptions;
+export type SimpleV4ThemeOptions = {
+  palette: PaletteOptions;
   defaultPageTheme: string;
   pageTheme?: Record<string, PageTheme>;
   fontFamily?: string;
diff --git a/packages/theme/src/index.ts b/packages/theme/src/index.ts
index 41f827bf43..33b5c9a697 100644
--- a/packages/theme/src/index.ts
+++ b/packages/theme/src/index.ts
@@ -1,5 +1,5 @@
 /*
- * Copyright 2020 The Backstage Authors
+ * Copyright 2022 The Backstage Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,7 +20,37 @@
  * @packageDocumentation
  */
 
-export * from './themes';
-export * from './baseTheme';
-export * from './types';
-export * from './pageTheme';
+export * from './v4';
+export type {
+  BackstagePaletteAdditions,
+  PageTheme,
+  PageThemeSelector,
+} from './types';
+
+import {
+  createV4Theme,
+  createV4ThemeOptions,
+  createV4ThemeOverrides,
+} from './v4';
+import type { SimpleV4ThemeOptions } from './v4';
+
+/**
+ * @public
+ * @deprecated Use {@link createV4Theme} instead.
+ */
+export const createTheme = createV4Theme;
+/**
+ * @public
+ * @deprecated Use {@link createV4ThemeOptions} instead.
+ */
+export const createThemeOptions = createV4ThemeOptions;
+/**
+ * @public
+ * @deprecated Use {@link createV4ThemeOverrides} instead.
+ */
+export const createThemeOverrides = createV4ThemeOverrides;
+/**
+ * @public
+ * @deprecated Use {@link SimpleV4ThemeOptions} instead.
+ */
+export type SimpleThemeOptions = SimpleV4ThemeOptions;
diff --git a/packages/theme/src/types.ts b/packages/theme/src/types.ts
index 0295e491f1..143ccbabaa 100644
--- a/packages/theme/src/types.ts
+++ b/packages/theme/src/types.ts
@@ -1,5 +1,5 @@
 /*
- * Copyright 2020 The Backstage Authors
+ * Copyright 2022 The Backstage Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,12 +14,6 @@
  * limitations under the License.
  */
 
-import { Theme, ThemeOptions } from '@material-ui/core';
-import {
-  PaletteOptions,
-  Palette,
-} from '@material-ui/core/styles/createPalette';
-
 /**
  * Backstage specific additions to the material-ui palette.
  *
@@ -90,21 +84,6 @@ export type BackstagePaletteAdditions = {
   };
 };
 
-/**
- * The full Backstage palette.
- *
- * @public
- */
-export type BackstagePalette = Palette & BackstagePaletteAdditions;
-
-/**
- * The full Backstage palette options.
- *
- * @public
- */
-export type BackstagePaletteOptions = PaletteOptions &
-  BackstagePaletteAdditions;
-
 /**
  * Selector for what page theme to use.
  *
@@ -114,48 +93,6 @@ export type PageThemeSelector = {
   themeId: string;
 };
 
-/**
- * A Backstage theme.
- *
- * @public
- */
-export interface BackstageTheme extends Theme {
-  palette: BackstagePalette;
-  page: PageTheme;
-  getPageTheme: (selector: PageThemeSelector) => PageTheme;
-}
-
-/**
- * Backstage theme options.
- *
- * @public
- * @remarks
- *
- * This is essentially a partial theme definition made by the user, that then
- * gets merged together with defaults and other values to form the final
- * {@link BackstageTheme}.
- *
- */
-export interface BackstageThemeOptions extends ThemeOptions {
-  palette: BackstagePaletteOptions;
-  page: PageTheme;
-  getPageTheme: (selector: PageThemeSelector) => PageTheme;
-}
-
-/**
- * A simpler configuration for creating a new theme that just tweaks some parts
- * of the backstage one.
- *
- * @public
- */
-export type SimpleThemeOptions = {
-  palette: BackstagePaletteOptions;
-  defaultPageTheme: string;
-  pageTheme?: Record<string, PageTheme>;
-  fontFamily?: string;
-  htmlFontSize?: number;
-};
-
 /**
  * The theme definitions for a given layout page.
  *
diff --git a/packages/theme/src/baseTheme.ts b/packages/theme/src/v4/baseTheme.ts
similarity index 93%
rename from packages/theme/src/baseTheme.ts
rename to packages/theme/src/v4/baseTheme.ts
index c0a9022bd0..b326018e87 100644
--- a/packages/theme/src/baseTheme.ts
+++ b/packages/theme/src/v4/baseTheme.ts
@@ -15,14 +15,11 @@
  */
 
 import { createTheme as createMuiTheme } from '@material-ui/core/styles';
+import { Theme, ThemeOptions } from '@material-ui/core';
 import { darken, lighten } from '@material-ui/core/styles/colorManipulator';
 import { Overrides } from '@material-ui/core/styles/overrides';
-import {
-  BackstageTheme,
-  BackstageThemeOptions,
-  SimpleThemeOptions,
-} from './types';
 import { pageTheme as defaultPageThemes } from './pageTheme';
+import { SimpleV4ThemeOptions } from './types';
 
 const DEFAULT_HTML_FONT_SIZE = 16;
 const DEFAULT_FONT_FAMILY =
@@ -33,9 +30,9 @@ const DEFAULT_FONT_FAMILY =
  *
  * @public
  */
-export function createThemeOptions(
-  options: SimpleThemeOptions,
-): BackstageThemeOptions {
+export function createV4ThemeOptions(
+  options: SimpleV4ThemeOptions,
+): ThemeOptions {
   const {
     palette,
     htmlFontSize = DEFAULT_HTML_FONT_SIZE,
@@ -103,7 +100,7 @@ export function createThemeOptions(
  *
  * @public
  */
-export function createThemeOverrides(theme: BackstageTheme): Overrides {
+export function createV4ThemeOverrides(theme: Theme): Overrides {
   return {
     MuiCssBaseline: {
       '@global': {
@@ -291,10 +288,10 @@ export function createThemeOverrides(theme: BackstageTheme): Overrides {
  *
  * @public
  */
-export function createTheme(options: SimpleThemeOptions): BackstageTheme {
-  const themeOptions = createThemeOptions(options);
-  const baseTheme = createMuiTheme(themeOptions) as BackstageTheme;
-  const overrides = createThemeOverrides(baseTheme);
+export function createV4Theme(options: SimpleV4ThemeOptions): Theme {
+  const themeOptions = createV4ThemeOptions(options);
+  const baseTheme = createMuiTheme(themeOptions);
+  const overrides = createV4ThemeOverrides(baseTheme);
   const theme = { ...baseTheme, overrides };
   return theme;
 }
diff --git a/packages/theme/src/v4/index.ts b/packages/theme/src/v4/index.ts
new file mode 100644
index 0000000000..f897070f0e
--- /dev/null
+++ b/packages/theme/src/v4/index.ts
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2020 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+export { darkTheme, lightTheme } from './themes';
+export {
+  createV4Theme,
+  createV4ThemeOptions,
+  createV4ThemeOverrides,
+} from './baseTheme';
+export type {
+  BackstagePalette,
+  BackstagePaletteOptions,
+  BackstageTheme,
+  BackstageThemeOptions,
+  SimpleV4ThemeOptions,
+} from './types';
+export { colorVariants, genPageTheme, pageTheme, shapes } from './pageTheme';
diff --git a/packages/theme/src/pageTheme.ts b/packages/theme/src/v4/pageTheme.ts
similarity index 99%
rename from packages/theme/src/pageTheme.ts
rename to packages/theme/src/v4/pageTheme.ts
index dd36d7641b..93eb2be0e3 100644
--- a/packages/theme/src/pageTheme.ts
+++ b/packages/theme/src/v4/pageTheme.ts
@@ -13,7 +13,8 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import { PageTheme } from './types';
+
+import { PageTheme } from '../types';
 
 /**
  * The default predefined burst shapes.
diff --git a/packages/theme/src/themes.ts b/packages/theme/src/v4/themes.ts
similarity index 96%
rename from packages/theme/src/themes.ts
rename to packages/theme/src/v4/themes.ts
index 23438a1c14..9432aa2b57 100644
--- a/packages/theme/src/themes.ts
+++ b/packages/theme/src/v4/themes.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import { createTheme } from './baseTheme';
+import { createV4Theme } from './baseTheme';
 import { pageTheme } from './pageTheme';
 import { yellow } from '@material-ui/core/colors';
 
@@ -23,7 +23,7 @@ import { yellow } from '@material-ui/core/colors';
  *
  * @public
  */
-export const lightTheme = createTheme({
+export const lightTheme = createV4Theme({
   palette: {
     type: 'light',
     background: {
@@ -101,7 +101,7 @@ export const lightTheme = createTheme({
  *
  * @public
  */
-export const darkTheme = createTheme({
+export const darkTheme = createV4Theme({
   palette: {
     type: 'dark',
     background: {
diff --git a/packages/theme/src/v4/types.ts b/packages/theme/src/v4/types.ts
new file mode 100644
index 0000000000..7a292fe0a1
--- /dev/null
+++ b/packages/theme/src/v4/types.ts
@@ -0,0 +1,105 @@
+/*
+ * Copyright 2020 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { Theme, ThemeOptions } from '@material-ui/core';
+import {
+  PaletteOptions,
+  Palette,
+} from '@material-ui/core/styles/createPalette';
+import {
+  BackstagePaletteAdditions,
+  PageTheme,
+  PageThemeSelector,
+} from '../types';
+
+/**
+ * The full Backstage palette.
+ *
+ * @public
+ * @deprecated This type is deprecated, the MUI Palette type is now always extended instead.
+ */
+export type BackstagePalette = Palette & BackstagePaletteAdditions;
+
+/**
+ * The full Backstage palette options.
+ *
+ * @public
+ * @deprecated This type is deprecated, the MUI PaletteOptions type is now always extended instead.
+ */
+export type BackstagePaletteOptions = PaletteOptions &
+  BackstagePaletteAdditions;
+
+/**
+ * Backstage theme options.
+ *
+ * @public
+ * @deprecated This type is deprecated, the MUI ThemeOptions type is now always extended instead.
+ * @remarks
+ *
+ * This is essentially a partial theme definition made by the user, that then
+ * gets merged together with defaults and other values to form the final
+ * {@link BackstageTheme}.
+ *
+ */
+export interface BackstageThemeOptions extends ThemeOptions {
+  palette: BackstagePaletteOptions;
+  page: PageTheme;
+  getPageTheme: (selector: PageThemeSelector) => PageTheme;
+}
+
+/**
+ * A Backstage theme.
+ *
+ * @public
+ * @deprecated This type is deprecated, the MUI Theme type is now always extended instead.
+ */
+export interface BackstageTheme extends Theme {
+  palette: BackstagePalette;
+  page: PageTheme;
+  getPageTheme: (selector: PageThemeSelector) => PageTheme;
+}
+
+/**
+ * A simpler configuration for creating a new theme that just tweaks some parts
+ * of the backstage one.
+ *
+ * @public
+ */
+export type SimpleV4ThemeOptions = {
+  palette: PaletteOptions;
+  defaultPageTheme: string;
+  pageTheme?: Record<string, PageTheme>;
+  fontFamily?: string;
+  htmlFontSize?: number;
+};
+
+declare module '@material-ui/core/styles/createPalette' {
+  interface Palette extends BackstagePaletteAdditions {}
+
+  interface PaletteOptions extends BackstagePaletteAdditions {}
+}
+
+declare module '@material-ui/core/styles/createTheme' {
+  interface Theme {
+    page: PageTheme;
+    getPageTheme: (selector: PageThemeSelector) => PageTheme;
+  }
+
+  interface ThemeOptions {
+    page: PageTheme;
+    getPageTheme: (selector: PageThemeSelector) => PageTheme;
+  }
+}