diff --git a/pkg/reconciler/knativeserving/ingress/ingress_test.go b/pkg/reconciler/knativeserving/ingress/ingress_test.go
index a4082b162..be4b1730b 100644
--- a/pkg/reconciler/knativeserving/ingress/ingress_test.go
+++ b/pkg/reconciler/knativeserving/ingress/ingress_test.go
@@ -58,7 +58,7 @@ func TestTransformers(t *testing.T) {
 				},
 			},
 		},
-		expected: 3,
+		expected: 4,
 	}, {
 		name: "Available contour ingress",
 		instance: servingv1beta1.KnativeServing{
@@ -109,7 +109,7 @@ func TestTransformers(t *testing.T) {
 				},
 			},
 		},
-		expected: 4,
+		expected: 5,
 	}}
 
 	for _, tt := range tests {
diff --git a/pkg/reconciler/knativeserving/ingress/kourier.go b/pkg/reconciler/knativeserving/ingress/kourier.go
index c2a858280..41a9393e3 100644
--- a/pkg/reconciler/knativeserving/ingress/kourier.go
+++ b/pkg/reconciler/knativeserving/ingress/kourier.go
@@ -19,6 +19,7 @@ package ingress
 import (
 	"context"
 	"fmt"
+	"strings"
 
 	mf "github.com/manifestival/manifestival"
 	appsv1 "k8s.io/api/apps/v1"
@@ -34,6 +35,8 @@ const (
 	kourierGatewayServiceName     = "kourier"
 	kourierDefaultVolumeName      = "kourier-bootstrap"
 	kourierGatewayDeploymentNames = "3scale-kourier-gateway"
+	kourierDefaultNamespace       = "knative-serving"
+	kourierBootstrapDataKey       = "envoy-bootstrap.yaml"
 )
 
 var kourierControllerDeploymentNames = sets.NewString("3scale-kourier-control", "net-kourier-controller")
@@ -41,6 +44,7 @@ var kourierControllerDeploymentNames = sets.NewString("3scale-kourier-control",
 func kourierTransformers(_ context.Context, instance *v1beta1.KnativeServing) []mf.Transformer {
 	return []mf.Transformer{
 		replaceGatewayNamespace(),
+		replaceBootstrapNamespace(),
 		configureGatewayService(instance),
 		configureBootstrapConfigMap(instance),
 	}
@@ -74,6 +78,28 @@ func replaceGatewayNamespace() mf.Transformer {
 	}
 }
 
+// replaceBootstrapNamespace updates namespace references embedded in Kourier's
+// default bootstrap configuration.
+func replaceBootstrapNamespace() mf.Transformer {
+	return func(u *unstructured.Unstructured) error {
+		if u.GetKind() != "ConfigMap" || u.GetName() != kourierDefaultVolumeName {
+			return nil
+		}
+
+		configMap := &v1.ConfigMap{}
+		if err := scheme.Scheme.Convert(u, configMap, nil); err != nil {
+			return err
+		}
+
+		if bootstrap, found := configMap.Data[kourierBootstrapDataKey]; found {
+			configMap.Data[kourierBootstrapDataKey] = strings.ReplaceAll(
+				bootstrap, kourierDefaultNamespace, configMap.GetNamespace())
+		}
+
+		return scheme.Scheme.Convert(configMap, u, nil)
+	}
+}
+
 func configureGatewayService(instance *v1beta1.KnativeServing) mf.Transformer {
 	return func(u *unstructured.Unstructured) error {
 		if u.GetKind() != "Service" || u.GetName() != kourierGatewayServiceName {
@@ -121,7 +147,7 @@ func configureGatewayService(instance *v1beta1.KnativeServing) mf.Transformer {
 	}
 }
 
-// configureBootstrapConfigMap sets Kourier GW's bootstrap configmap name.
+// configureBootstrapConfigMap sets Kourier GW's bootstrap ConfigMap name.
 func configureBootstrapConfigMap(instance *v1beta1.KnativeServing) mf.Transformer {
 	return func(u *unstructured.Unstructured) error {
 		if u.GetKind() == "Deployment" && u.GetName() == kourierGatewayDeploymentNames {
diff --git a/pkg/reconciler/knativeserving/ingress/kourier_test.go b/pkg/reconciler/knativeserving/ingress/kourier_test.go
index 2f6b353b8..e73c10178 100644
--- a/pkg/reconciler/knativeserving/ingress/kourier_test.go
+++ b/pkg/reconciler/knativeserving/ingress/kourier_test.go
@@ -18,6 +18,7 @@ package ingress
 
 import (
 	"fmt"
+	"strings"
 	"testing"
 
 	mf "github.com/manifestival/manifestival"
@@ -182,6 +183,61 @@ func TestTransformKourierManifest(t *testing.T) {
 	}
 }
 
+func TestReplaceBootstrapNamespace(t *testing.T) {
+	const customNamespace = "custom-serving"
+
+	client := fake.New()
+	manifest, err := mf.NewManifest("testdata/kodata/ingress/1.9/kourier/kourier.yaml", mf.UseClient(client))
+	if err != nil {
+		t.Fatalf("Failed to read manifest: %v", err)
+	}
+
+	before := bootstrapConfigMap(t, manifest)
+	defaultControllerAddress := "net-kourier-controller." + kourierDefaultNamespace
+	if bootstrap := before.Data[kourierBootstrapDataKey]; !strings.Contains(bootstrap, defaultControllerAddress) {
+		t.Fatalf("Bootstrap config does not contain default controller address %q", defaultControllerAddress)
+	}
+
+	manifest, err = manifest.Transform(
+		mf.InjectNamespace(customNamespace),
+		replaceBootstrapNamespace(),
+	)
+	if err != nil {
+		t.Fatalf("Failed to transform manifest: %v", err)
+	}
+
+	after := bootstrapConfigMap(t, manifest)
+	if after.Namespace != customNamespace {
+		t.Fatalf("Bootstrap ConfigMap namespace = %q, want %q", after.Namespace, customNamespace)
+	}
+	bootstrap := after.Data[kourierBootstrapDataKey]
+	if strings.Contains(bootstrap, kourierDefaultNamespace) {
+		t.Fatalf("Bootstrap config still contains default namespace %q", kourierDefaultNamespace)
+	}
+	if want := "net-kourier-controller." + customNamespace; !strings.Contains(bootstrap, want) {
+		t.Fatalf("Bootstrap config does not contain controller address %q", want)
+	}
+}
+
+func bootstrapConfigMap(t *testing.T, manifest mf.Manifest) *v1.ConfigMap {
+	t.Helper()
+
+	for _, u := range manifest.Resources() {
+		if u.GetKind() != "ConfigMap" || u.GetName() != kourierDefaultVolumeName {
+			continue
+		}
+
+		configMap := &v1.ConfigMap{}
+		if err := scheme.Scheme.Convert(&u, configMap, nil); err != nil {
+			t.Fatalf("Failed to convert bootstrap ConfigMap: %v", err)
+		}
+		return configMap
+	}
+
+	t.Fatal("Bootstrap ConfigMap not found")
+	return nil
+}
+
 func verifyGatewayServiceTypeNodePortHTTP(t *testing.T, u *unstructured.Unstructured, expHTTPPort int32) {
 	if u.GetKind() == "Service" && u.GetName() == kourierGatewayServiceName {
 		svc := &v1.Service{}