diff --git a/projects/plugins/wpcomsh/changelog/fix-launch-banner-in-iframe b/projects/plugins/wpcomsh/changelog/fix-launch-banner-in-iframe
new file mode 100644
index 0000000000000..3d25f5d5bcb47
--- /dev/null
+++ b/projects/plugins/wpcomsh/changelog/fix-launch-banner-in-iframe
@@ -0,0 +1,4 @@
+Significance: patch
+Type: fixed
+
+Gutenberg 19.9: don't show launch banner when the site is previewed in Appearance -> Design
diff --git a/projects/plugins/wpcomsh/private-site/logged-in-banner.php b/projects/plugins/wpcomsh/private-site/logged-in-banner.php
index 28bd6cdeb0560..b478ff329c70c 100644
--- a/projects/plugins/wpcomsh/private-site/logged-in-banner.php
+++ b/projects/plugins/wpcomsh/private-site/logged-in-banner.php
@@ -199,6 +199,11 @@ function show_logged_in_banner() {
 
 			el.style.display = 'none';
 			document.addEventListener( 'DOMContentLoaded', function() {
+				// Don't show the banner if the site is previewed via an iframe.
+				if ( window.top !== window.self ) {
+					return;
+				}
+
 				var el = document.querySelector( '#wpcom-launch-banner-wrapper' );
 				if ( el ) {
 					el.style.display = null;