diff --git a/src/wp-includes/class-wp-block-type.php b/src/wp-includes/class-wp-block-type.php
index 86f0ea21a2a3c..b52ad134338dd 100644
--- a/src/wp-includes/class-wp-block-type.php
+++ b/src/wp-includes/class-wp-block-type.php
@@ -536,6 +536,7 @@ public function prepare_attributes_for_render( $attributes ) {
 	 * Sets block type properties.
 	 *
 	 * @since 5.0.0
+	 * @since 7.1.0 Added Support for rich-text attribute type, which is normalized to string for server-side rendering.
 	 *
 	 * @param array|string $args Array or string of arguments for registering a block type.
 	 *                           See WP_Block_Type::__construct() for information on accepted arguments.
@@ -562,6 +563,16 @@ public function set_props( $args ) {
 			}
 		}
 
+		// Normalize block attribute types. The 'rich-text' type is used in
+		// block.json for the editor, but is not a valid JSON Schema type.
+		// Map it to 'string' since rich text values are always strings on
+		// the server side.
+		foreach ( $args['attributes'] as $key => $attribute ) {
+			if ( isset( $attribute['type'] ) && 'rich-text' === $attribute['type'] ) {
+				$args['attributes'][ $key ]['type'] = 'string';
+			}
+		}
+
 		/**
 		 * Filters the arguments for registering a block type.
 		 *
diff --git a/tests/phpunit/tests/blocks/wpBlockType.php b/tests/phpunit/tests/blocks/wpBlockType.php
index a73efa8ce8a7d..6a7fdb72729b8 100644
--- a/tests/phpunit/tests/blocks/wpBlockType.php
+++ b/tests/phpunit/tests/blocks/wpBlockType.php
@@ -211,6 +211,7 @@ public function test_prepare_attributes() {
 			/* missingDefaulted */
 			'undefined'          => 'include',
 			'intendedNull'       => null,
+			'richtext'           => 'rich text content',
 		);
 
 		$block_type = new WP_Block_Type(
@@ -235,6 +236,9 @@ public function test_prepare_attributes() {
 						'type'    => array( 'string', 'null' ),
 						'default' => 'wrong',
 					),
+					'richtext'           => array(
+						'type' => 'rich-text',
+					),
 				),
 			)
 		);
@@ -249,6 +253,7 @@ public function test_prepare_attributes() {
 				'missingDefaulted'   => 'define',
 				'undefined'          => 'include',
 				'intendedNull'       => null,
+				'richtext'           => 'rich text content',
 			),
 			$prepared_attributes
 		);