diff --git a/wp-admin/includes/update-core.php b/wp-admin/includes/update-core.php
index fdb522c889..5f5c7a9ab6 100644
--- a/wp-admin/includes/update-core.php
+++ b/wp-admin/includes/update-core.php
@@ -997,6 +997,7 @@ $_new_bundled_files = array(
 	'themes/twentytwentyone/'   => '5.6',
 	'themes/twentytwentytwo/'   => '5.9',
 	'themes/twentytwentythree/' => '6.1',
+	'themes/twentytwentyfour/'  => '6.4',
 );
 
 /**
diff --git a/wp-includes/class-wp-theme.php b/wp-includes/class-wp-theme.php
index 479a5b5cb1..d7c36440ee 100644
--- a/wp-includes/class-wp-theme.php
+++ b/wp-includes/class-wp-theme.php
@@ -59,6 +59,7 @@ final class WP_Theme implements ArrayAccess {
 	 * @since 5.6.0 Added the Twenty Twenty-One theme.
 	 * @since 5.9.0 Added the Twenty Twenty-Two theme.
 	 * @since 6.1.0 Added the Twenty Twenty-Three theme.
+	 * @since 6.4.0 Added the Twenty Twenty-Four theme.
 	 * @var string[]
 	 */
 	private static $default_themes = array(
@@ -77,6 +78,7 @@ final class WP_Theme implements ArrayAccess {
 		'twentytwentyone'   => 'Twenty Twenty-One',
 		'twentytwentytwo'   => 'Twenty Twenty-Two',
 		'twentytwentythree' => 'Twenty Twenty-Three',
+		'twentytwentyfour'  => 'Twenty Twenty-Four',
 	);
 
 	/**
diff --git a/wp-includes/default-constants.php b/wp-includes/default-constants.php
index 0c0ee771eb..5bccc204cd 100644
--- a/wp-includes/default-constants.php
+++ b/wp-includes/default-constants.php
@@ -431,6 +431,6 @@ function wp_templating_constants() {
 	 * @see WP_Theme::get_core_default_theme()
 	 */
 	if ( ! defined( 'WP_DEFAULT_THEME' ) ) {
-		define( 'WP_DEFAULT_THEME', 'twentytwentythree' );
+		define( 'WP_DEFAULT_THEME', 'twentytwentyfour' );
 	}
 }
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 513838cc17..e61e64769f 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.4-alpha-56726';
+$wp_version = '6.4-alpha-56727';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.