diff --git a/src/wp-includes/rest-api/endpoints/class-wp-rest-plugins-controller.php b/src/wp-includes/rest-api/endpoints/class-wp-rest-plugins-controller.php
index 3fb36bff1e..28b51d7612 100644
--- a/src/wp-includes/rest-api/endpoints/class-wp-rest-plugins-controller.php
+++ b/src/wp-includes/rest-api/endpoints/class-wp-rest-plugins-controller.php
@@ -548,7 +548,7 @@ class WP_REST_Plugins_Controller extends WP_REST_Controller {
 			'network_only' => $item['Network'],
 			'requires_wp'  => $item['RequiresWP'],
 			'requires_php' => $item['RequiresPHP'],
-			'text_domain'  => $item['TextDomain'],
+			'textdomain'   => $item['TextDomain'],
 		);
 
 		$data = $this->add_additional_fields_to_object( $data, $request );
@@ -908,7 +908,7 @@ class WP_REST_Plugins_Controller extends WP_REST_Controller {
 					'readonly'    => true,
 					'context'     => array( 'view', 'edit', 'embed' ),
 				),
-				'text_domain'  => array(
+				'textdomain'   => array(
 					'description' => __( 'The plugin\'s text domain.' ),
 					'type'        => 'string',
 					'readonly'    => true,
diff --git a/tests/phpunit/tests/rest-api/rest-plugins-controller.php b/tests/phpunit/tests/rest-api/rest-plugins-controller.php
index 77203a73d3..30bec793b4 100644
--- a/tests/phpunit/tests/rest-api/rest-plugins-controller.php
+++ b/tests/phpunit/tests/rest-api/rest-plugins-controller.php
@@ -977,7 +977,7 @@ class WP_REST_Plugins_Controller_Test extends WP_Test_REST_Controller_Testcase {
 		$this->assertArrayHasKey( 'network_only', $properties );
 		$this->assertArrayHasKey( 'requires_wp', $properties );
 		$this->assertArrayHasKey( 'requires_php', $properties );
-		$this->assertArrayHasKey( 'text_domain', $properties );
+		$this->assertArrayHasKey( 'textdomain', $properties );
 	}
 
 	/**
@@ -1001,7 +1001,7 @@ class WP_REST_Plugins_Controller_Test extends WP_Test_REST_Controller_Testcase {
 		$this->assertEquals( $network_only, $data['network_only'] );
 		$this->assertEquals( '5.6.0', $data['requires_php'] );
 		$this->assertEquals( '5.4.0', $data['requires_wp'] );
-		$this->assertEquals( 'test-plugin', $data['text_domain'] );
+		$this->assertEquals( 'test-plugin', $data['textdomain'] );
 	}
 
 	/**