diff --git a/projects/plugins/social/changelog/add-reply-to-support-social-notes b/projects/plugins/social/changelog/add-reply-to-support-social-notes
new file mode 100644
index 0000000000000..9e7a0738be21b
--- /dev/null
+++ b/projects/plugins/social/changelog/add-reply-to-support-social-notes
@@ -0,0 +1,4 @@
+Significance: minor
+Type: added
+
+Social Notes: add support for the ActivityPub Reply-To block.
diff --git a/projects/plugins/social/src/class-note.php b/projects/plugins/social/src/class-note.php
index 2f47673513ffb..c1326f7f66683 100644
--- a/projects/plugins/social/src/class-note.php
+++ b/projects/plugins/social/src/class-note.php
@@ -7,6 +7,8 @@
 
 namespace Automattic\Jetpack\Social;
 
+use Automattic\Jetpack\Constants;
+
 /**
  * Register the Jetpack Social Note custom post type.
  */
@@ -31,6 +33,19 @@ public function init() {
 		}
 		add_filter( 'allowed_block_types', array( $this, 'restrict_blocks_for_social_note' ), 10, 2 );
 
+		/*
+		 * The ActivityPub plugin has a block to set a Fediverse post that a new post is in reply to. This is perfect for Social Notes.
+		 */
+		if ( Constants::get_constant( 'ACTIVITYPUB_PLUGIN_VERSION' ) ) {
+			add_filter(
+				'jetpack_social_allowed_blocks',
+				function ( $allowed_blocks ) {
+					$allowed_blocks[] = 'activitypub/reply';
+					return $allowed_blocks;
+				}
+			);
+		}
+
 		self::register_cpt();
 		add_action( 'wp_insert_post_data', array( $this, 'set_empty_title' ), 10, 2 );
 		add_action( 'admin_init', array( $this, 'admin_init_actions' ) );
@@ -148,7 +163,16 @@ public function restrict_blocks_for_social_note( $allowed_blocks, $post ) {
 			);
 		}
 
-		return $allowed_blocks;
+		/**
+		 * Filters the blocks available to the Social Notes CPT.
+		 *
+		 * Default is ['core/paragraph', 'core/post-featured-image']
+		 *
+		 * @since $$next-version$$
+		 *
+		 * @param array $allowed_blocks A linear array of blocks allowed by the CPT.
+		 */
+		return apply_filters( 'jetpack_social_allowed_blocks', $allowed_blocks );
 	}
 
 	/**