diff --git a/lib/client-assets.php b/lib/client-assets.php
index ab2cd25426a7ea..7e7f3800b791b2 100644
--- a/lib/client-assets.php
+++ b/lib/client-assets.php
@@ -708,7 +708,8 @@ function gutenberg_extend_block_editor_settings_with_fse_theme_flag( $settings )
  * Sets the editor styles to be consumed by JS.
  */
 function gutenberg_extend_block_editor_styles_html() {
-	$handles = array(
+	$script_handles = array();
+	$style_handles  = array(
 		'wp-block-editor',
 		'wp-block-library',
 		'wp-block-library-theme',
@@ -719,26 +720,48 @@ function gutenberg_extend_block_editor_styles_html() {
 
 	foreach ( $block_registry->get_all_registered() as $block_type ) {
 		if ( ! empty( $block_type->style ) ) {
-			$handles[] = $block_type->style;
+			$style_handles[] = $block_type->style;
 		}
 
 		if ( ! empty( $block_type->editor_style ) ) {
-			$handles[] = $block_type->editor_style;
+			$style_handles[] = $block_type->editor_style;
+		}
+
+		if ( ! empty( $block_type->script ) ) {
+			$script_handles[] = $block_type->script;
 		}
 	}
 
-	$handles = array_unique( $handles );
-	$done    = wp_styles()->done;
+	$style_handles = array_unique( $style_handles );
+	$done          = wp_styles()->done;
 
 	ob_start();
 
 	wp_styles()->done = array();
-	wp_styles()->do_items( $handles );
+	wp_styles()->do_items( $style_handles );
 	wp_styles()->done = $done;
 
-	$editor_styles = wp_json_encode( array( 'html' => ob_get_clean() ) );
+	$styles = ob_get_clean();
+
+	$script_handles = array_unique( $script_handles );
+	$done           = wp_scripts()->done;
+
+	ob_start();
+
+	wp_scripts()->done = array();
+	wp_scripts()->do_items( $script_handles );
+	wp_scripts()->done = $done;
+
+	$scripts = ob_get_clean();
+
+	$editor_assets = wp_json_encode(
+		array(
+			'styles'  => $styles,
+			'scripts' => $scripts,
+		)
+	);
 
-	echo "<script>window.__editorStyles = $editor_styles</script>";
+	echo "<script>window.__editorAssets = $editor_assets</script>";
 }
 add_action( 'admin_footer-toplevel_page_gutenberg-edit-site', 'gutenberg_extend_block_editor_styles_html' );
 add_action( 'admin_footer-post.php', 'gutenberg_extend_block_editor_styles_html' );
diff --git a/packages/block-editor/src/components/iframe/index.js b/packages/block-editor/src/components/iframe/index.js
index 3570bb1bd6ad11..93d298632cfab6 100644
--- a/packages/block-editor/src/components/iframe/index.js
+++ b/packages/block-editor/src/components/iframe/index.js
@@ -6,6 +6,8 @@ import {
 	createPortal,
 	useCallback,
 	forwardRef,
+	useEffect,
+	useMemo,
 } from '@wordpress/element';
 import { __ } from '@wordpress/i18n';
 import { useMergeRefs } from '@wordpress/compose';
@@ -133,21 +135,33 @@ function setBodyClassName( doc ) {
 	}
 }
 
-/**
- * Sets the document head and default styles.
- *
- * @param {Document} doc  Document to set the head for.
- * @param {string}   head HTML to set as the head.
- */
-function setHead( doc, head ) {
-	doc.head.innerHTML =
-		// Body margin must be overridable by themes.
-		'<style>body{margin:0}</style>' + head;
+function useParsedAssets( html ) {
+	return useMemo( () => {
+		const doc = document.implementation.createHTMLDocument( '' );
+		doc.body.innerHTML = html;
+		return Array.from( doc.body.children );
+	}, [ html ] );
 }
 
-function Iframe( { contentRef, children, head, headHTML, ...props }, ref ) {
-	const [ iframeDocument, setIframeDocument ] = useState();
+async function loadScript( doc, { id, src } ) {
+	return new Promise( ( resolve, reject ) => {
+		const script = doc.createElement( 'script' );
+		script.id = id;
+		if ( src ) {
+			script.src = src;
+			script.onload = () => resolve();
+			script.onerror = () => reject();
+		} else {
+			resolve();
+		}
+		doc.head.appendChild( script );
+	} );
+}
 
+function Iframe( { contentRef, children, head, ...props }, ref ) {
+	const [ iframeDocument, setIframeDocument ] = useState();
+	const styles = useParsedAssets( window.__editorAssets.styles );
+	const scripts = useParsedAssets( window.__editorAssets.scripts );
 	const clearerRef = useBlockSelectionClearer();
 	const setRef = useCallback( ( node ) => {
 		if ( ! node ) {
@@ -168,15 +182,19 @@ function Iframe( { contentRef, children, head, headHTML, ...props }, ref ) {
 				contentRef.current = body;
 			}
 
-			setHead( contentDocument, headHTML );
 			setBodyClassName( contentDocument );
-			styleSheetsCompat( contentDocument );
 			bubbleEvents( contentDocument );
 			setBodyClassName( contentDocument );
 			setIframeDocument( contentDocument );
 			clearerRef( documentElement );
 			clearerRef( body );
 
+			scripts.reduce(
+				( promise, script ) =>
+					promise.then( () => loadScript( contentDocument, script ) ),
+				Promise.resolve()
+			);
+
 			return true;
 		}
 
@@ -190,6 +208,25 @@ function Iframe( { contentRef, children, head, headHTML, ...props }, ref ) {
 		} );
 	}, [] );
 
+	useEffect( () => {
+		if ( iframeDocument ) {
+			styleSheetsCompat( iframeDocument );
+		}
+	}, [ iframeDocument ] );
+
+	head = (
+		<>
+			<style>{ 'body{margin:0}' }</style>
+			{ styles.map( ( { tagName, href, id, rel, media }, index ) => {
+				const TagName = tagName.toLowerCase();
+				return (
+					<TagName { ...{ href, id, rel, media } } key={ index } />
+				);
+			} ) }
+			{ head }
+		</>
+	);
+
 	return (
 		<iframe
 			{ ...props }
diff --git a/packages/edit-post/src/components/visual-editor/index.js b/packages/edit-post/src/components/visual-editor/index.js
index 853a1ba633a3ff..8f25b84a917de7 100644
--- a/packages/edit-post/src/components/visual-editor/index.js
+++ b/packages/edit-post/src/components/visual-editor/index.js
@@ -70,7 +70,6 @@ function MaybeIframe( {
 
 	return (
 		<Iframe
-			headHTML={ window.__editorStyles.html }
 			head={ <EditorStyles styles={ styles } /> }
 			ref={ ref }
 			contentRef={ contentRef }
diff --git a/packages/edit-site/src/components/block-editor/index.js b/packages/edit-site/src/components/block-editor/index.js
index e168c40f7f2589..ebe97e3e7ea7b5 100644
--- a/packages/edit-site/src/components/block-editor/index.js
+++ b/packages/edit-site/src/components/block-editor/index.js
@@ -87,7 +87,6 @@ export default function BlockEditor( { setIsInserterOpen } ) {
 				<BlockTools __unstableContentRef={ contentRef }>
 					<Iframe
 						style={ resizedCanvasStyles }
-						headHTML={ window.__editorStyles.html }
 						head={ <EditorStyles styles={ settings.styles } /> }
 						ref={ ref }
 						contentRef={ mergedRefs }