diff --git a/wp-includes/block-template-utils.php b/wp-includes/block-template-utils.php
index f3eaf7b95a..3aba7f381d 100644
--- a/wp-includes/block-template-utils.php
+++ b/wp-includes/block-template-utils.php
@@ -542,6 +542,7 @@ function _remove_theme_attribute_in_block_template_content( $template_content )
  * Builds a unified template object based on a theme file.
  *
  * @since 5.9.0
+ * @since 6.3.0 Added `modified` property to template objects.
  * @access private
  *
  * @param array  $template_file Theme file.
@@ -564,6 +565,7 @@ function _build_block_template_result_from_file( $template_file, $template_type
 	$template->status         = 'publish';
 	$template->has_theme_file = true;
 	$template->is_custom      = true;
+	$template->modified       = null;
 
 	if ( 'wp_template' === $template_type && isset( $default_template_types[ $template_file['slug'] ] ) ) {
 		$template->description = $default_template_types[ $template_file['slug'] ]['description'];
@@ -743,6 +745,7 @@ function _wp_build_title_and_description_for_taxonomy_block_template( $taxonomy,
  * Builds a unified template object based a post Object.
  *
  * @since 5.9.0
+ * @since 6.3.0 Added `modified` property to template objects.
  * @access private
  *
  * @param WP_Post $post Template post.
@@ -782,6 +785,7 @@ function _build_block_template_result_from_post( $post ) {
 	$template->has_theme_file = $has_theme_file;
 	$template->is_custom      = empty( $is_wp_suggestion );
 	$template->author         = $post->post_author;
+	$template->modified       = $post->post_modified;
 
 	if ( 'wp_template' === $post->post_type && $has_theme_file && isset( $template_file['postTypes'] ) ) {
 		$template->post_types = $template_file['postTypes'];
diff --git a/wp-includes/class-wp-block-template.php b/wp-includes/class-wp-block-template.php
index 75bfd4747d..8149935203 100644
--- a/wp-includes/class-wp-block-template.php
+++ b/wp-includes/class-wp-block-template.php
@@ -146,4 +146,12 @@ class WP_Block_Template {
 	 * @var string|null
 	 */
 	public $area;
+
+	/**
+	 * Modified.
+	 *
+	 * @since 6.3.0
+	 * @var string|null
+	 */
+	public $modified;
 }
diff --git a/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php b/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php
index df8a3dcd6d..d1854c5073 100644
--- a/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php
+++ b/wp-includes/rest-api/endpoints/class-wp-rest-templates-controller.php
@@ -614,6 +614,7 @@ class WP_REST_Templates_Controller extends WP_REST_Controller {
 	 *
 	 * @since 5.8.0
 	 * @since 5.9.0 Renamed `$template` to `$item` to match parent class for PHP 8 named parameter support.
+	 * @since 6.3.0 Added `modified` property to the response.
 	 *
 	 * @param WP_Block_Template $item    Template instance.
 	 * @param WP_REST_Request   $request Request object.
@@ -708,6 +709,10 @@ class WP_REST_Templates_Controller extends WP_REST_Controller {
 			$data['area'] = $template->area;
 		}
 
+		if ( rest_is_field_included( 'modified', $fields ) ) {
+			$data['modified'] = mysql_to_rfc3339( $template->modified );
+		}
+
 		$context = ! empty( $request['context'] ) ? $request['context'] : 'view';
 		$data    = $this->add_additional_fields_to_object( $data, $request );
 		$data    = $this->filter_response_by_context( $data, $context );
@@ -926,6 +931,13 @@ class WP_REST_Templates_Controller extends WP_REST_Controller {
 					'type'        => 'integer',
 					'context'     => array( 'view', 'edit', 'embed' ),
 				),
+				'modified'       => array(
+					'description' => __( "The date the template was last modified, in the site's timezone." ),
+					'type'        => 'string',
+					'format'      => 'date-time',
+					'context'     => array( 'view', 'edit' ),
+					'readonly'    => true,
+				),
 			),
 		);
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 2586b8ddc5..9c0521072d 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.3-alpha-55991';
+$wp_version = '6.3-alpha-55992';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.