diff --git a/lib/class-wp-theme-json-gutenberg.php b/lib/class-wp-theme-json-gutenberg.php
index 9acef6006d4e68..cd1f683c1a5d6b 100644
--- a/lib/class-wp-theme-json-gutenberg.php
+++ b/lib/class-wp-theme-json-gutenberg.php
@@ -2818,7 +2818,12 @@ public static function remove_insecure_properties( $theme_json ) {
 				continue;
 			}
 
-			$output = static::remove_insecure_styles( $input );
+			// The global styles custom CSS is not sanitized, but can only be edited by users with 'edit_css' capability.
+			if ( isset( $input['css'] ) && current_user_can( 'edit_css' ) ) {
+				$output = $input;
+			} else {
+				$output = static::remove_insecure_styles( $input );
+			}
 
 			/*
 			 * Get a reference to element name from path.
diff --git a/lib/experimental/kses.php b/lib/experimental/kses.php
index fd7531617939fc..830ac01c2ab0b6 100644
--- a/lib/experimental/kses.php
+++ b/lib/experimental/kses.php
@@ -62,5 +62,6 @@ function gutenberg_override_core_kses_init_filters() {
 	}
 
 }
-add_action( 'init', 'gutenberg_override_core_kses_init_filters' );
+// The 'kses_init_filters' is usually initialized with default priority. Use higher priority to override.
+add_action( 'init', 'gutenberg_override_core_kses_init_filters', 20 );
 add_action( 'set_current_user', 'gutenberg_override_core_kses_init_filters' );
diff --git a/phpunit/class-wp-theme-json-test.php b/phpunit/class-wp-theme-json-test.php
index 0d21f46ee9c291..795ad0ab4c8117 100644
--- a/phpunit/class-wp-theme-json-test.php
+++ b/phpunit/class-wp-theme-json-test.php
@@ -7,6 +7,36 @@
  */
 
 class WP_Theme_JSON_Gutenberg_Test extends WP_UnitTestCase {
+	/**
+	 * Administrator ID.
+	 *
+	 * @var int
+	 */
+	private static $administrator_id;
+
+	/**
+	 * User ID.
+	 *
+	 * @var int
+	 */
+	private static $user_id;
+
+	public static function set_up_before_class() {
+		parent::set_up_before_class();
+
+		static::$administrator_id = self::factory()->user->create(
+			array(
+				'role' => 'administrator',
+			)
+		);
+
+		if ( is_multisite() ) {
+			grant_super_admin( self::$administrator_id );
+		}
+
+		static::$user_id = self::factory()->user->create();
+	}
+
 	/**
 	 * @dataProvider data_get_layout_definitions
 	 *
@@ -1598,4 +1628,73 @@ public function test_get_stylesheet_handles_custom_css() {
 		$custom_css = 'body { color:purple; }';
 		$this->assertEquals( $custom_css, $theme_json->get_stylesheet( array( 'custom-css' ) ) );
 	}
+
+	/**
+	 * @dataProvider data_custom_css_for_user_caps
+	 *
+	 * @param string $user_property The property name for current user.
+	 * @param array  $expected      Expected results.
+	 */
+	public function test_custom_css_for_user_caps( $user_property, array $expected ) {
+		wp_set_current_user( static::${$user_property} );
+
+		$actual = WP_Theme_JSON_Gutenberg::remove_insecure_properties(
+			array(
+				'version' => WP_Theme_JSON_Gutenberg::LATEST_SCHEMA,
+				'styles'  => array(
+					'css'    => 'body { color:purple; }',
+					'blocks' => array(
+						'core/separator' => array(
+							'color' => array(
+								'background' => 'blue',
+							),
+						),
+					),
+				),
+			)
+		);
+
+		$this->assertSameSetsWithIndex( $expected, $actual );
+	}
+
+	/**
+	 * Data provider.
+	 *
+	 * @return array[]
+	 */
+	public function data_custom_css_for_user_caps() {
+		return array(
+			'allows custom css for users with caps'     => array(
+				'user_property' => 'administrator_id',
+				'expected'      => array(
+					'version' => WP_Theme_JSON_Gutenberg::LATEST_SCHEMA,
+					'styles'  => array(
+						'css'    => 'body { color:purple; }',
+						'blocks' => array(
+							'core/separator' => array(
+								'color' => array(
+									'background' => 'blue',
+								),
+							),
+						),
+					),
+				),
+			),
+			'removes custom css for users without caps' => array(
+				'user_property' => 'user_id',
+				'expected'      => array(
+					'version' => WP_Theme_JSON_Gutenberg::LATEST_SCHEMA,
+					'styles'  => array(
+						'blocks' => array(
+							'core/separator' => array(
+								'color' => array(
+									'background' => 'blue',
+								),
+							),
+						),
+					),
+				),
+			),
+		);
+	}
 }