diff --git a/packages/components/CHANGELOG.md b/packages/components/CHANGELOG.md
index 927b1a12cee4c..b23d024a724dd 100644
--- a/packages/components/CHANGELOG.md
+++ b/packages/components/CHANGELOG.md
@@ -6,6 +6,8 @@
 
 -   `DimensionControl`: Deprecate 36px default size ([#66705](https://github.com/WordPress/gutenberg/pull/66705)).
 -   `TextControl`: Deprecate 36px default size ([#66745](https://github.com/WordPress/gutenberg/pull/66745).
+-   `FontSizePicker`: Deprecate 36px default size ([#66920](https://github.com/WordPress/gutenberg/pull/66920)).
+-   `ComboboxControl`: Deprecate 36px default size ([#66900](https://github.com/WordPress/gutenberg/pull/66900)).
 
 ### Bug Fixes
 
@@ -30,7 +32,6 @@
 ### Deprecations
 
 -   `Radio`: Deprecate 36px default size ([#66572](https://github.com/WordPress/gutenberg/pull/66572)).
--   `ComboboxControl`: Deprecate 36px default size ([#66900](https://github.com/WordPress/gutenberg/pull/66900)).
 
 ### Bug Fixes
 
diff --git a/packages/components/src/font-size-picker/README.md b/packages/components/src/font-size-picker/README.md
index 5d7fe2b39a737..39d916c0c7b21 100644
--- a/packages/components/src/font-size-picker/README.md
+++ b/packages/components/src/font-size-picker/README.md
@@ -29,6 +29,7 @@ const MyFontSizePicker = () => {
 
 	return (
 		<FontSizePicker
+			__next40pxDefaultSize
 			fontSizes={ fontSizes }
 			value={ fontSize }
 			fallbackFontSize={ fallbackFontSize }
diff --git a/packages/components/src/font-size-picker/index.tsx b/packages/components/src/font-size-picker/index.tsx
index f93a09440a068..d4e8ea29fc6c4 100644
--- a/packages/components/src/font-size-picker/index.tsx
+++ b/packages/components/src/font-size-picker/index.tsx
@@ -35,6 +35,7 @@ import { Spacer } from '../spacer';
 import FontSizePickerSelect from './font-size-picker-select';
 import FontSizePickerToggleGroup from './font-size-picker-toggle-group';
 import { T_SHIRT_NAMES } from './constants';
+import { maybeWarnDeprecated36pxSize } from '../utils/deprecated-36px-size';
 
 const DEFAULT_UNITS = [ 'px', 'em', 'rem', 'vw', 'vh' ];
 
@@ -123,6 +124,12 @@ const UnforwardedFontSizePicker = (
 		!! valueUnit && [ 'em', 'rem', 'vw', 'vh' ].includes( valueUnit );
 	const isDisabled = value === undefined;
 
+	maybeWarnDeprecated36pxSize( {
+		componentName: 'FontSizePicker',
+		__next40pxDefaultSize,
+		size,
+	} );
+
 	return (
 		<Container ref={ ref } className="components-font-size-picker">
 			<VisuallyHidden as="legend">{ __( 'Font size' ) }</VisuallyHidden>
diff --git a/packages/components/src/font-size-picker/stories/index.story.tsx b/packages/components/src/font-size-picker/stories/index.story.tsx
index eec8f5173d965..a0d83756ca1ec 100644
--- a/packages/components/src/font-size-picker/stories/index.story.tsx
+++ b/packages/components/src/font-size-picker/stories/index.story.tsx
@@ -66,6 +66,7 @@ const TwoFontSizePickersWithState: StoryFn< typeof FontSizePicker > = ( {
 export const Default: StoryFn< typeof FontSizePicker > =
 	FontSizePickerWithState.bind( {} );
 Default.args = {
+	__next40pxDefaultSize: true,
 	disableCustomFontSizes: false,
 	fontSizes: [
 		{
diff --git a/packages/components/src/font-size-picker/test/index.tsx b/packages/components/src/font-size-picker/test/index.tsx
index e7205e57eefaa..34e8ce17c67fa 100644
--- a/packages/components/src/font-size-picker/test/index.tsx
+++ b/packages/components/src/font-size-picker/test/index.tsx
@@ -8,13 +8,17 @@ import { render } from '@ariakit/test/react';
 /**
  * Internal dependencies
  */
-import FontSizePicker from '../';
+import _FontSizePicker from '../';
 import type { FontSize } from '../types';
 /**
  * WordPress dependencies
  */
 import { useState } from '@wordpress/element';
 
+const FontSizePicker = (
+	props: React.ComponentProps< typeof _FontSizePicker >
+) => <_FontSizePicker __next40pxDefaultSize { ...props } />;
+
 const ControlledFontSizePicker = ( {
 	onChange,
 	...props