diff --git a/packages/components/CHANGELOG.md b/packages/components/CHANGELOG.md
index 630b26bad2f797..5fd48336f956c1 100644
--- a/packages/components/CHANGELOG.md
+++ b/packages/components/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 ### Enhancements
 
+-   `MenuItem`: Add 40px size prop on Button ([#66596](https://github.com/WordPress/gutenberg/pull/66596)).
 -   `Guide`: Use small size button for page controls ([#66607](https://github.com/WordPress/gutenberg/pull/66607)).
 -   `PaletteEdit`: Add appropriate size props to Buttons ([#66590](https://github.com/WordPress/gutenberg/pull/66590)).
 -   `Notice`: Add appropriate size props to Buttons ([#66593](https://github.com/WordPress/gutenberg/pull/66593)).
diff --git a/packages/components/src/menu-item/index.tsx b/packages/components/src/menu-item/index.tsx
index cb746becdbb1ba..cc57d23e585a10 100644
--- a/packages/components/src/menu-item/index.tsx
+++ b/packages/components/src/menu-item/index.tsx
@@ -56,6 +56,7 @@ function UnforwardedMenuItem(
 
 	return (
 		<Button
+			__next40pxDefaultSize
 			ref={ ref }
 			// Make sure aria-checked matches spec https://www.w3.org/TR/wai-aria-1.1/#aria-checked
 			aria-checked={
diff --git a/packages/components/src/menu-item/test/__snapshots__/index.js.snap b/packages/components/src/menu-item/test/__snapshots__/index.js.snap
index 06aaf4b620dfe0..07dc49b034e5ee 100644
--- a/packages/components/src/menu-item/test/__snapshots__/index.js.snap
+++ b/packages/components/src/menu-item/test/__snapshots__/index.js.snap
@@ -3,7 +3,7 @@
 exports[`MenuItem should match snapshot when all props provided 1`] = `
 <button
   aria-checked="true"
-  class="components-button components-menu-item__button my-class"
+  class="components-button components-menu-item__button my-class is-next-40px-default-size"
   role="menuitemcheckbox"
   type="button"
 >
@@ -35,7 +35,7 @@ exports[`MenuItem should match snapshot when all props provided 1`] = `
 
 exports[`MenuItem should match snapshot when info is provided 1`] = `
 <button
-  class="components-button components-menu-item__button"
+  class="components-button components-menu-item__button is-next-40px-default-size"
   role="menuitem"
   type="button"
 >
@@ -62,7 +62,7 @@ exports[`MenuItem should match snapshot when info is provided 1`] = `
 
 exports[`MenuItem should match snapshot when isSelected and role are optionally provided 1`] = `
 <button
-  class="components-button components-menu-item__button my-class"
+  class="components-button components-menu-item__button my-class is-next-40px-default-size"
   role="menuitem"
   type="button"
 >
@@ -94,7 +94,7 @@ exports[`MenuItem should match snapshot when isSelected and role are optionally
 
 exports[`MenuItem should match snapshot when only label provided 1`] = `
 <button
-  class="components-button components-menu-item__button"
+  class="components-button components-menu-item__button is-next-40px-default-size"
   role="menuitem"
   type="button"
 >