diff --git a/src/wp-includes/block-supports/layout.php b/src/wp-includes/block-supports/layout.php
index 70d1fe4255..67d6a3f1b7 100644
--- a/src/wp-includes/block-supports/layout.php
+++ b/src/wp-includes/block-supports/layout.php
@@ -638,7 +638,7 @@ function wp_render_layout_support_flag( $block_content, $block ) {
 	 * for features like the enhanced pagination of the Query block.
 	 */
 	$container_class = wp_unique_prefixed_id(
-		'wp-container-' . sanitize_title( $block['blockName'] ) . '-layout-'
+		'wp-container-' . sanitize_title( $block['blockName'] ) . '-is-layout-'
 	);
 
 	// Set the correct layout type for blocks using legacy content width.
@@ -883,17 +883,45 @@ function wp_restore_group_inner_container( $block_content, $block ) {
 		return $block_content;
 	}
 
-	$replace_regex   = sprintf(
+	/*
+	 * This filter runs after the layout classnames have been added to the block, so they
+	 * have to be removed from the outer wrapper and then added to the inner.
+	 */
+	$layout_classes = array();
+	$processor      = new WP_HTML_Tag_Processor( $block_content );
+
+	if ( $processor->next_tag( array( 'class_name' => 'wp-block-group' ) ) ) {
+		foreach ( $processor->class_list() as $class_name ) {
+			if ( str_contains( $class_name, 'is-layout-' ) ) {
+				$layout_classes[] = $class_name;
+				$processor->remove_class( $class_name );
+			}
+		}
+	}
+
+	$content_without_layout_classes = $processor->get_updated_html();
+	$replace_regex                  = sprintf(
 		'/(^\s*<%1$s\b[^>]*wp-block-group[^>]*>)(.*)(<\/%1$s>\s*$)/ms',
 		preg_quote( $tag_name, '/' )
 	);
-	$updated_content = preg_replace_callback(
+	$updated_content                = preg_replace_callback(
 		$replace_regex,
 		static function ( $matches ) {
 			return $matches[1] . '<div class="wp-block-group__inner-container">' . $matches[2] . '</div>' . $matches[3];
 		},
-		$block_content
+		$content_without_layout_classes
 	);
+
+	// Add layout classes to inner wrapper.
+	if ( ! empty( $layout_classes ) ) {
+		$processor = new WP_HTML_Tag_Processor( $updated_content );
+		if ( $processor->next_tag( array( 'class_name' => 'wp-block-group__inner-container' ) ) ) {
+			foreach ( $layout_classes as $class_name ) {
+				$processor->add_class( $class_name );
+			}
+		}
+		$updated_content = $processor->get_updated_html();
+	}
 	return $updated_content;
 }
 
diff --git a/tests/phpunit/tests/block-supports/layout.php b/tests/phpunit/tests/block-supports/layout.php
index df0abf9b49..379c10fe2b 100644
--- a/tests/phpunit/tests/block-supports/layout.php
+++ b/tests/phpunit/tests/block-supports/layout.php
@@ -252,4 +252,94 @@ class Test_Block_Supports_Layout extends WP_UnitTestCase {
 			),
 		);
 	}
+
+	/**
+	 * Check that wp_restore_group_inner_container() restores the legacy inner container on the Group block.
+	 *
+	 * @ticket 60130
+	 *
+	 * @covers ::wp_restore_group_inner_container
+	 *
+	 * @dataProvider data_restore_group_inner_container
+	 *
+	 * @param array  $args            Dataset to test.
+	 * @param string $expected_output The expected output.
+	 */
+	public function test_restore_group_inner_container( $args, $expected_output ) {
+		$actual_output = wp_restore_group_inner_container( $args['block_content'], $args['block'] );
+		$this->assertEquals( $expected_output, $actual_output );
+	}
+
+	/**
+	 * Data provider for test_restore_group_inner_container.
+	 *
+	 * @return array
+	 */
+	public function data_restore_group_inner_container() {
+		return array(
+			'group block with existing inner container'    => array(
+				'args'            => array(
+					'block_content' => '<div class="wp-block-group"><div class="wp-block-group__inner-container"></div></div>',
+					'block'         => array(
+						'blockName'    => 'core/group',
+						'attrs'        => array(
+							'layout' => array(
+								'type' => 'default',
+							),
+						),
+						'innerBlocks'  => array(),
+						'innerHTML'    => '<div class="wp-block-group"><div class="wp-block-group__inner-container"></div></div>',
+						'innerContent' => array(
+							'<div class="wp-block-group"><div class="wp-block-group__inner-container">',
+							' ',
+							' </div></div>',
+						),
+					),
+				),
+				'expected_output' => '<div class="wp-block-group"><div class="wp-block-group__inner-container"></div></div>',
+			),
+			'group block with no existing inner container' => array(
+				'args'            => array(
+					'block_content' => '<div class="wp-block-group"></div>',
+					'block'         => array(
+						'blockName'    => 'core/group',
+						'attrs'        => array(
+							'layout' => array(
+								'type' => 'default',
+							),
+						),
+						'innerBlocks'  => array(),
+						'innerHTML'    => '<div class="wp-block-group"></div>',
+						'innerContent' => array(
+							'<div class="wp-block-group">',
+							' ',
+							' </div>',
+						),
+					),
+				),
+				'expected_output' => '<div class="wp-block-group"><div class="wp-block-group__inner-container"></div></div>',
+			),
+			'group block with layout classnames'           => array(
+				'args'            => array(
+					'block_content' => '<div class="wp-block-group is-layout-constrained wp-block-group-is-layout-constrained"></div>',
+					'block'         => array(
+						'blockName'    => 'core/group',
+						'attrs'        => array(
+							'layout' => array(
+								'type' => 'default',
+							),
+						),
+						'innerBlocks'  => array(),
+						'innerHTML'    => '<div class="wp-block-group"></div>',
+						'innerContent' => array(
+							'<div class="wp-block-group">',
+							' ',
+							' </div>',
+						),
+					),
+				),
+				'expected_output' => '<div class="wp-block-group"><div class="wp-block-group__inner-container is-layout-constrained wp-block-group-is-layout-constrained"></div></div>',
+			),
+		);
+	}
 }