diff --git a/staging/src/k8s.io/apiserver/pkg/endpoints/handlers/metrics/metrics.go b/staging/src/k8s.io/apiserver/pkg/endpoints/handlers/metrics/metrics.go
index 91a7999680d..57766924c19 100644
--- a/staging/src/k8s.io/apiserver/pkg/endpoints/handlers/metrics/metrics.go
+++ b/staging/src/k8s.io/apiserver/pkg/endpoints/handlers/metrics/metrics.go
@@ -18,8 +18,10 @@ package metrics
 
 import (
 	"context"
+	"sync"
 
 	"k8s.io/component-base/metrics"
+	"k8s.io/component-base/metrics/legacyregistry"
 )
 
 type RequestBodyVerb string
@@ -47,6 +49,15 @@ var (
 	)
 )
 
+var registerMetrics sync.Once
+
+// Register all metrics.
+func Register() {
+	registerMetrics.Do(func() {
+		legacyregistry.MustRegister(RequestBodySizes)
+	})
+}
+
 func RecordRequestBodySize(ctx context.Context, resource string, verb RequestBodyVerb, size int) {
 	RequestBodySizes.WithContext(ctx).WithLabelValues(resource, string(verb)).Observe(float64(size))
 }
diff --git a/staging/src/k8s.io/apiserver/pkg/server/routes/metrics.go b/staging/src/k8s.io/apiserver/pkg/server/routes/metrics.go
index ad1eb2835ef..8fd4d559999 100644
--- a/staging/src/k8s.io/apiserver/pkg/server/routes/metrics.go
+++ b/staging/src/k8s.io/apiserver/pkg/server/routes/metrics.go
@@ -17,6 +17,7 @@ limitations under the License.
 package routes
 
 import (
+	handlersmetrics "k8s.io/apiserver/pkg/endpoints/handlers/metrics"
 	apimetrics "k8s.io/apiserver/pkg/endpoints/metrics"
 	"k8s.io/apiserver/pkg/server/mux"
 	cachermetrics "k8s.io/apiserver/pkg/storage/cacher/metrics"
@@ -52,4 +53,5 @@ func register() {
 	etcd3metrics.Register()
 	flowcontrolmetrics.Register()
 	peerproxymetrics.Register()
+	handlersmetrics.Register()
 }