diff --git a/src/wp-includes/rest-api/endpoints/class-wp-rest-controller.php b/src/wp-includes/rest-api/endpoints/class-wp-rest-controller.php
index 0d1e85cbf1..44880aaec2 100644
--- a/src/wp-includes/rest-api/endpoints/class-wp-rest-controller.php
+++ b/src/wp-includes/rest-api/endpoints/class-wp-rest-controller.php
@@ -645,6 +645,7 @@ abstract class WP_REST_Controller {
 			'pattern',
 			'minItems',
 			'maxItems',
+			'uniqueItems',
 		);
 
 		foreach ( $schema_properties as $field_id => $params ) {
diff --git a/tests/phpunit/tests/rest-api/rest-controller.php b/tests/phpunit/tests/rest-api/rest-controller.php
index b04158b037..b68300e270 100644
--- a/tests/phpunit/tests/rest-api/rest-controller.php
+++ b/tests/phpunit/tests/rest-api/rest-controller.php
@@ -265,7 +265,7 @@ class WP_Test_REST_Controller extends WP_Test_REST_TestCase {
 
 		$this->assertArrayHasKey( 'items', $args['somearray'] );
 
-		foreach ( array( 'minItems', 'maxItems' ) as $property ) {
+		foreach ( array( 'minItems', 'maxItems', 'uniqueItems' ) as $property ) {
 			$this->assertArrayHasKey( $property, $args['somearray'] );
 		}
 
diff --git a/tests/phpunit/tests/rest-api/rest-test-controller.php b/tests/phpunit/tests/rest-api/rest-test-controller.php
index e3a82586bc..35175f35b1 100644
--- a/tests/phpunit/tests/rest-api/rest-test-controller.php
+++ b/tests/phpunit/tests/rest-api/rest-test-controller.php
@@ -101,13 +101,14 @@ class WP_REST_Test_Controller extends WP_REST_Controller {
 					'default' => 'a',
 				),
 				'somearray'      => array(
-					'type'     => 'array',
-					'items'    => array(
+					'type'        => 'array',
+					'items'       => array(
 						'type' => 'string',
 					),
-					'minItems' => 1,
-					'maxItems' => 10,
-					'context'  => array( 'view' ),
+					'minItems'    => 1,
+					'maxItems'    => 10,
+					'uniqueItems' => true,
+					'context'     => array( 'view' ),
 				),
 				'someobject'     => array(
 					'type'                 => 'object',