diff --git a/apis/core/v1beta1/openstackcontrolplane_webhook.go b/apis/core/v1beta1/openstackcontrolplane_webhook.go
index 8b4edaf23..99464fbf1 100644
--- a/apis/core/v1beta1/openstackcontrolplane_webhook.go
+++ b/apis/core/v1beta1/openstackcontrolplane_webhook.go
@@ -17,6 +17,7 @@ limitations under the License.
 package v1beta1
 
 import (
+	"context"
 	"fmt"
 	"strings"
 
@@ -26,11 +27,14 @@ import (
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/util/validation/field"
 	ctrl "sigs.k8s.io/controller-runtime"
+	"sigs.k8s.io/controller-runtime/pkg/client"
 	logf "sigs.k8s.io/controller-runtime/pkg/log"
 	"sigs.k8s.io/controller-runtime/pkg/webhook"
 	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
 )
 
+var ctlplaneWebhookClient client.Client
+
 // OpenStackControlPlaneDefaults -
 type OpenStackControlPlaneDefaults struct {
 	RabbitMqImageURL string
@@ -49,6 +53,10 @@ func SetupOpenStackControlPlaneDefaults(defaults OpenStackControlPlaneDefaults)
 
 // SetupWebhookWithManager sets up the Webhook with the Manager.
 func (r *OpenStackControlPlane) SetupWebhookWithManager(mgr ctrl.Manager) error {
+	if ctlplaneWebhookClient == nil {
+		ctlplaneWebhookClient = mgr.GetClient()
+	}
+
 	return ctrl.NewWebhookManagedBy(mgr).
 		For(r).
 		Complete()
@@ -64,6 +72,38 @@ func (r *OpenStackControlPlane) ValidateCreate() (admission.Warnings, error) {
 
 	var allErrs field.ErrorList
 	basePath := field.NewPath("spec")
+
+	ctlplaneList := &OpenStackControlPlaneList{}
+	listOpts := []client.ListOption{
+		client.InNamespace(r.Namespace),
+	}
+	if err := ctlplaneWebhookClient.List(context.TODO(), ctlplaneList, listOpts...); err != nil {
+		return nil, apierrors.NewForbidden(
+			schema.GroupResource{
+				Group:    GroupVersion.WithKind("OpenStackControlPlane").Group,
+				Resource: GroupVersion.WithKind("OpenStackControlPlane").Kind,
+			}, r.GetName(), &field.Error{
+				Type:     field.ErrorTypeForbidden,
+				Field:    "",
+				BadValue: r.Name,
+				Detail:   err.Error(),
+			},
+		)
+	}
+	if len(ctlplaneList.Items) >= 1 {
+		return nil, apierrors.NewForbidden(
+			schema.GroupResource{
+				Group:    GroupVersion.WithKind("OpenStackControlPlane").Group,
+				Resource: GroupVersion.WithKind("OpenStackControlPlane").Kind,
+			}, r.GetName(), &field.Error{
+				Type:     field.ErrorTypeForbidden,
+				Field:    "",
+				BadValue: r.Name,
+				Detail:   "Only one OpenStackControlPlane instance per namespace is supported at this time.",
+			},
+		)
+	}
+
 	if err := r.ValidateCreateServices(basePath); err != nil {
 		allErrs = append(allErrs, err...)
 	}
diff --git a/tests/functional/openstackoperator_controller_test.go b/tests/functional/openstackoperator_controller_test.go
index cc0c66535..0f089a15c 100644
--- a/tests/functional/openstackoperator_controller_test.go
+++ b/tests/functional/openstackoperator_controller_test.go
@@ -1673,6 +1673,41 @@ var _ = Describe("OpenStackOperator controller", func() {
 
 var _ = Describe("OpenStackOperator Webhook", func() {
 
+	It("Blocks creating multiple ctlplane CRs in the same namespace", func() {
+		spec := GetDefaultOpenStackControlPlaneSpec()
+		spec["tls"] = GetTLSPublicSpec()
+		DeferCleanup(
+			th.DeleteInstance,
+			CreateOpenStackControlPlane(names.OpenStackControlplaneName, spec),
+		)
+
+		OSCtlplane := GetOpenStackControlPlane(names.OpenStackControlplaneName)
+		Expect(OSCtlplane.Labels).Should(Not(BeNil()))
+		Expect(OSCtlplane.Labels).Should(HaveKeyWithValue("core.openstack.org/openstackcontrolplane", ""))
+
+		raw := map[string]interface{}{
+			"apiVersion": "core.openstack.org/v1beta1",
+			"kind":       "OpenStackControlPlane",
+			"metadata": map[string]interface{}{
+				"name":      "foo",
+				"namespace": OSCtlplane.GetNamespace(),
+			},
+			"spec": spec,
+		}
+
+		unstructuredObj := &unstructured.Unstructured{Object: raw}
+		_, err := controllerutil.CreateOrPatch(
+			th.Ctx, th.K8sClient, unstructuredObj, func() error { return nil })
+		Expect(err).Should(HaveOccurred())
+		var statusError *k8s_errors.StatusError
+		Expect(errors.As(err, &statusError)).To(BeTrue())
+		Expect(statusError.ErrStatus.Details.Kind).To(Equal("OpenStackControlPlane"))
+		Expect(statusError.ErrStatus.Message).To(
+			ContainSubstring(
+				"Forbidden: Only one OpenStackControlPlane instance per namespace is supported at this time."),
+		)
+	})
+
 	It("Adds default label via defaulting webhook", func() {
 		spec := GetDefaultOpenStackControlPlaneSpec()
 		spec["tls"] = GetTLSPublicSpec()