diff --git src/wp-includes/option.php src/wp-includes/option.php
index aa98477..aad0830 100644
--- src/wp-includes/option.php
+++ src/wp-includes/option.php
@@ -1737,13 +1737,19 @@ function register_initial_settings() {
 		'description'  => __( 'Site tagline.' ),
 	) );
 
-	register_setting( 'general', 'siteurl', array(
-		'show_in_rest' => array(
+	if ( is_multisite() ) {
+		$siteurl_in_rest = false;
+	} else {
+		$siteurl_in_rest = array(
 			'name'    => 'url',
 			'schema'  => array(
 				'format' => 'uri',
 			),
-		),
+		);
+	}
+
+	register_setting( 'general', 'siteurl', array(
+		'show_in_rest' => $siteurl_in_rest,
 		'type'         => 'string',
 		'description'  => __( 'Site URL.' ),
 	) );
diff --git tests/phpunit/tests/rest-api/rest-settings-controller.php tests/phpunit/tests/rest-api/rest-settings-controller.php
index ff91a60..bf30d31 100644
--- tests/phpunit/tests/rest-api/rest-settings-controller.php
+++ tests/phpunit/tests/rest-api/rest-settings-controller.php
@@ -50,24 +50,45 @@ class WP_Test_REST_Settings_Controller extends WP_Test_REST_Controller_Testcase
 		$response = $this->server->dispatch( $request );
 		$data = $response->get_data();
 
+		if ( is_multisite() ) {
+			$expected = array(
+				'title',
+				'description',
+				'email',
+				'timezone',
+				'date_format',
+				'time_format',
+				'start_of_week',
+				'language',
+				'use_smilies',
+				'default_category',
+				'default_post_format',
+				'posts_per_page',
+				'default_ping_status',
+				'default_comment_status',
+			);
+		} else {
+			$expected = array(
+				'title',
+				'description',
+				'url',
+				'email',
+				'timezone',
+				'date_format',
+				'time_format',
+				'start_of_week',
+				'language',
+				'use_smilies',
+				'default_category',
+				'default_post_format',
+				'posts_per_page',
+				'default_ping_status',
+				'default_comment_status',
+			);
+		}
+
 		$this->assertEquals( 200, $response->get_status() );
-		$this->assertEquals( array(
-			'title',
-			'description',
-			'url',
-			'email',
-			'timezone',
-			'date_format',
-			'time_format',
-			'start_of_week',
-			'language',
-			'use_smilies',
-			'default_category',
-			'default_post_format',
-			'posts_per_page',
-			'default_ping_status',
-			'default_comment_status',
-		), array_keys( $data ) );
+		$this->assertEquals( $expected, array_keys( $data ) );
 	}
 
 	public function test_get_item_value_is_cast_to_type() {