diff --git a/src/wp-includes/theme.php b/src/wp-includes/theme.php
index ee544e25dc..c3d5003f75 100644
--- a/src/wp-includes/theme.php
+++ b/src/wp-includes/theme.php
@@ -3804,6 +3804,7 @@ function _wp_keep_alive_customize_changeset_dependent_auto_drafts( $new_status,
  * See {@see 'setup_theme'}.
  *
  * @since 5.5.0
+ * @since 6.1.0 The `block-templates` feature was added.
  */
 function create_initial_theme_features() {
 	register_theme_feature(
@@ -3820,6 +3821,13 @@ function create_initial_theme_features() {
 			'show_in_rest' => true,
 		)
 	);
+	register_theme_feature(
+		'block-templates',
+		array(
+			'description'  => __( 'Whether a theme uses block-based templates.' ),
+			'show_in_rest' => true,
+		)
+	);
 	register_theme_feature(
 		'custom-background',
 		array(
diff --git a/tests/phpunit/tests/rest-api/rest-themes-controller.php b/tests/phpunit/tests/rest-api/rest-themes-controller.php
index 6737a707bd..36818f8976 100644
--- a/tests/phpunit/tests/rest-api/rest-themes-controller.php
+++ b/tests/phpunit/tests/rest-api/rest-themes-controller.php
@@ -387,6 +387,7 @@ class WP_Test_REST_Themes_Controller extends WP_Test_REST_Controller_Testcase {
 		$theme_supports = $properties['theme_supports']['properties'];
 		$this->assertArrayHasKey( 'align-wide', $theme_supports );
 		$this->assertArrayHasKey( 'automatic-feed-links', $theme_supports );
+		$this->assertArrayHasKey( 'block-templates', $theme_supports );
 		$this->assertArrayHasKey( 'custom-header', $theme_supports );
 		$this->assertArrayHasKey( 'custom-background', $theme_supports );
 		$this->assertArrayHasKey( 'custom-logo', $theme_supports );
@@ -405,7 +406,7 @@ class WP_Test_REST_Themes_Controller extends WP_Test_REST_Controller_Testcase {
 		$this->assertArrayHasKey( 'responsive-embeds', $theme_supports );
 		$this->assertArrayHasKey( 'title-tag', $theme_supports );
 		$this->assertArrayHasKey( 'wp-block-styles', $theme_supports );
-		$this->assertCount( 20, $theme_supports );
+		$this->assertCount( 21, $theme_supports );
 	}
 
 	/**