diff --git a/src/wp-includes/rest-api/class-wp-rest-server.php b/src/wp-includes/rest-api/class-wp-rest-server.php
index 12de6c55f0..771c3b9fbe 100644
--- a/src/wp-includes/rest-api/class-wp-rest-server.php
+++ b/src/wp-includes/rest-api/class-wp-rest-server.php
@@ -879,16 +879,17 @@ class WP_REST_Server {
 		$method = $request->get_method();
 		$path   = $request->get_route();
 
-		$routes = array();
+		$with_namespace = array();
 
 		foreach ( $this->get_namespaces() as $namespace ) {
-			if ( 0 === strpos( ltrim( $path, '/' ), $namespace ) ) {
-				$routes = $this->get_routes( $namespace );
-				break;
+			if ( 0 === strpos( trailingslashit( ltrim( $path, '/' ) ), $namespace ) ) {
+				$with_namespace[] = $this->get_routes( $namespace );
 			}
 		}
 
-		if ( ! $routes ) {
+		if ( $with_namespace ) {
+			$routes = array_merge( ...$with_namespace );
+		} else {
 			$routes = $this->get_routes();
 		}
 
diff --git a/tests/phpunit/tests/rest-api/rest-server.php b/tests/phpunit/tests/rest-api/rest-server.php
index b724221891..8f178bff2b 100644
--- a/tests/phpunit/tests/rest-api/rest-server.php
+++ b/tests/phpunit/tests/rest-api/rest-server.php
@@ -1465,6 +1465,37 @@ class Tests_REST_Server extends WP_Test_REST_TestCase {
 		}
 	}
 
+	/**
+	 * @ticket 48530
+	 */
+	public function test_get_routes_no_namespace_overriding() {
+		register_rest_route(
+			'test-ns',
+			'/test',
+			array(
+				'methods'  => array( 'GET' ),
+				'callback' => function() {
+					return new WP_REST_Response( 'data', 204 );
+				},
+			)
+		);
+		register_rest_route(
+			'test-ns/v1',
+			'/test',
+			array(
+				'methods'  => array( 'GET' ),
+				'callback' => function() {
+					return new WP_REST_Response( 'data', 204 );
+				},
+			)
+		);
+
+		$request  = new WP_REST_Request( 'GET', '/test-ns/v1/test' );
+		$response = rest_get_server()->dispatch( $request );
+
+		$this->assertEquals( 204, $response->get_status(), '/test-ns/v1/test' );
+	}
+
 	public function _validate_as_integer_123( $value, $request, $key ) {
 		if ( ! is_int( $value ) ) {
 			return new WP_Error( 'some-error', 'This is not valid!' );