diff --git a/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php b/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
index 008124d582..85af10f5f6 100644
--- a/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
+++ b/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
@@ -653,6 +653,26 @@ class WP_REST_Posts_Controller extends WP_REST_Controller {
 
 		$prepared_post->post_type = $this->post_type;
 
+		if ( ! empty( $prepared_post->post_name )
+			&& ! empty( $prepared_post->post_status )
+			&& in_array( $prepared_post->post_status, array( 'draft', 'pending' ), true )
+		) {
+			/*
+			 * `wp_unique_post_slug()` returns the same
+			 * slug for 'draft' or 'pending' posts.
+			 *
+			 * To ensure that a unique slug is generated,
+			 * pass the post data with the 'publish' status.
+			 */
+			$prepared_post->post_name = wp_unique_post_slug(
+				$prepared_post->post_name,
+				$prepared_post->id,
+				'publish',
+				$prepared_post->post_type,
+				$prepared_post->post_parent
+			);
+		}
+
 		$post_id = wp_insert_post( wp_slash( (array) $prepared_post ), true, false );
 
 		if ( is_wp_error( $post_id ) ) {
@@ -834,6 +854,24 @@ class WP_REST_Posts_Controller extends WP_REST_Controller {
 			return $post;
 		}
 
+		if ( ! empty( $post->post_status ) ) {
+			$post_status = $post->post_status;
+		} else {
+			$post_status = $post_before->post_status;
+		}
+
+		/*
+		 * `wp_unique_post_slug()` returns the same
+		 * slug for 'draft' or 'pending' posts.
+		 *
+		 * To ensure that a unique slug is generated,
+		 * pass the post data with the 'publish' status.
+		 */
+		if ( ! empty( $post->post_name ) && in_array( $post_status, array( 'draft', 'pending' ), true ) ) {
+			$post_parent     = ! empty( $post->post_parent ) ? $post->post_parent : 0;
+			$post->post_name = wp_unique_post_slug( $post->post_name, $post->ID, 'publish', $post->post_type, $post_parent );
+		}
+
 		// Convert the post object to an array, otherwise wp_update_post() will expect non-escaped input.
 		$post_id = wp_update_post( wp_slash( (array) $post ), true, false );
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index ebba86053b..25bfbbd406 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.1-alpha-53812';
+$wp_version = '6.1-alpha-53813';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.