diff --git a/core/lib/Drupal/Core/Routing/RequestFormatRouteFilter.php b/core/lib/Drupal/Core/Routing/RequestFormatRouteFilter.php
index 8119efa07b..4456157254 100644
--- a/core/lib/Drupal/Core/Routing/RequestFormatRouteFilter.php
+++ b/core/lib/Drupal/Core/Routing/RequestFormatRouteFilter.php
@@ -26,9 +26,17 @@ public function filter(RouteCollection $collection, Request $request) {
     $format = $request->getRequestFormat('html');
     /** @var \Symfony\Component\Routing\Route $route */
     foreach ($collection as $name => $route) {
+      $supported_formats = array_filter(explode('|', $route->getRequirement('_format')));
+      $default_format = $route->getDefault('_default_format');
+
       // If the route has no _format specification, we move it to the end. If it
       // does, then no match means the route is removed entirely.
-      if ($supported_formats = array_filter(explode('|', $route->getRequirement('_format')))) {
+      if ($supported_formats) {
+        // If the route has a matching default format, use it
+        if ($default_format && in_array($default_format, $supported_formats)) {
+          $request->setRequestFormat($default_format);
+          $format = $default_format;
+        }
         if (!in_array($format, $supported_formats)) {
           $collection->remove($name);
         }
diff --git a/core/modules/rest/src/Routing/ResourceRoutes.php b/core/modules/rest/src/Routing/ResourceRoutes.php
index 8aedfba59e..df07625916 100644
--- a/core/modules/rest/src/Routing/ResourceRoutes.php
+++ b/core/modules/rest/src/Routing/ResourceRoutes.php
@@ -116,6 +116,14 @@ protected function getRoutesForResourceConfig(RestResourceConfigInterface $rest_
         // authentication provider and add the route.
         $route->setOption('_auth', $rest_resource_config->getAuthenticationProviders($method));
         $route->setDefault('_rest_resource_config', $rest_resource_config->id());
+
+        if (($config = $rest_resource_config->get('configuration')) &&
+          isset($config['default_format'])
+        ) {
+          $default_format = $config['default_format'];
+          $route->setDefault('_default_format', $default_format);
+        }
+
         $collection->add("rest.$name", $route);
       }

diff --git a/core/tests/Drupal/Tests/Core/Routing/RequestFormatRouteFilterTest.php b/core/tests/Drupal/Tests/Core/Routing/RequestFormatRouteFilterTest.php
index 4a9e0c6..0f592c9 100644
--- a/core/tests/Drupal/Tests/Core/Routing/RequestFormatRouteFilterTest.php
+++ b/core/tests/Drupal/Tests/Core/Routing/RequestFormatRouteFilterTest.php
@@ -76,6 +76,27 @@ class RequestFormatRouteFilterTest extends UnitTestCase {
   /**
    * @covers ::filter
    */
+  public function testDefaultRoute() {
+    $route_filter = new RequestFormatRouteFilter();
+
+    $route_with_default_format = $route = new Route('/test');
+    $route_with_default_format->setRequirement('_format', 'json');
+    $route_with_default_format->setDefault('_default_format', 'json');
+
+    $collection = new RouteCollection();
+    $collection->add('test_r_with_default', $route_with_default_format);
+
+    $request = new Request();
+    $request->setRequestFormat('html');
+    $collection = $route_filter->filter($collection, $request);
+
+    $this->assertCount(1, $collection);
+    $this->assertEquals(array_keys($collection->all())[0], 'test_r_with_default');
+  }
+
+  /**
+   * @covers ::filter
+   */
   public function testNoRouteFound() {
     $collection = new RouteCollection();
     $route_with_format = $route = new Route('/test');