diff --git a/cmd/main.go b/cmd/main.go
index 767d203f..c05624e0 100644
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -45,8 +45,12 @@ func main() {
 	var metricsAddr string
 	var enableLeaderElection bool
 	var probeAddr string
+	var watchNamespaces string
 	flag.StringVar(&metricsAddr, "metrics-bind-address", ":8080", "The address the metric endpoint binds to.")
 	flag.StringVar(&probeAddr, "health-probe-bind-address", ":8081", "The address the probe endpoint binds to.")
+	flag.StringVar(&watchNamespaces, "watch-namespaces", "",
+		"Comma-separated list of namespaces the controller watches. "+
+			"If empty, the controller watches all namespaces.")
 	flag.BoolVar(&enableLeaderElection, "leader-elect", false,
 		"Enable leader election for controller manager. "+
 			"Enabling this will ensure there is only one active controller manager.")
@@ -56,10 +60,19 @@ func main() {
 	opts.BindFlags(flag.CommandLine)
 	flag.Parse()
 
+	if watchNamespaces == "" {
+		watchNamespaces = os.Getenv("WATCH_NAMESPACES")
+	}
+	namespaces := controller.ParseWatchNamespaces(watchNamespaces)
+
 	//ctrl.SetLogger(zap.New(zap.UseFlagOptions(&opts)))
 	ctrl.SetLogger(zap.New(zap.JSONEncoder()))
 
-	cacheOptions, err := controller.NewCacheOptions()
+	if len(namespaces) > 0 {
+		setupLog.Info("running controller in namespace-scoped mode", "namespaces", namespaces)
+	}
+
+	cacheOptions, err := controller.NewCacheOptions(namespaces)
 	if err != nil {
 		setupLog.Error(err, "unable to build manager cache options")
 		os.Exit(1)
@@ -86,6 +99,7 @@ func main() {
 		// after the manager stops then its usage might be unsafe.
 		// LeaderElectionReleaseOnCancel: true,
 	})
+
 	if err != nil {
 		setupLog.Error(err, "unable to start manager")
 		os.Exit(1)
diff --git a/helm/temporal-worker-controller/templates/_helpers.tpl b/helm/temporal-worker-controller/templates/_helpers.tpl
index 5b143384..41fb9871 100644
--- a/helm/temporal-worker-controller/templates/_helpers.tpl
+++ b/helm/temporal-worker-controller/templates/_helpers.tpl
@@ -18,3 +18,19 @@ Used for matchLabels (Deployments, Services, affinities, etc.)
 app.kubernetes.io/name: temporal-worker-controller
 app.kubernetes.io/instance: {{ .Release.Name }}
 {{- end }}
+
+{{/*
+Namespace selector restricting admission webhooks to the watched namespaces.
+Rendered only when rbac.restrictWatchNamespaces is set; keys off the
+kubernetes.io/metadata.name label the API server sets on every namespace.
+*/}}
+{{- define "temporal-worker-controller.webhookNamespaceSelector" -}}
+namespaceSelector:
+  matchExpressions:
+    - key: kubernetes.io/metadata.name
+      operator: In
+      values:
+      {{- range .Values.rbac.restrictWatchNamespaces }}
+        - {{ . | quote }}
+      {{- end }}
+{{- end }}
diff --git a/helm/temporal-worker-controller/templates/manager.yaml b/helm/temporal-worker-controller/templates/manager.yaml
index a6e66c82..06bac819 100644
--- a/helm/temporal-worker-controller/templates/manager.yaml
+++ b/helm/temporal-worker-controller/templates/manager.yaml
@@ -98,6 +98,10 @@ spec:
         {{- end }}
         - name: ALLOWED_KINDS
           value: {{ join "," $allKinds | quote }}
+        {{- with .Values.rbac.restrictWatchNamespaces }}
+        - name: WATCH_NAMESPACES
+          value: {{ join "," . | quote }}
+        {{- end }}
         args:
         - --leader-elect
         {{- if .Values.metrics.enabled }}
diff --git a/helm/temporal-worker-controller/templates/rbac.yaml b/helm/temporal-worker-controller/templates/rbac.yaml
index 83614c3f..cf3e9ba2 100644
--- a/helm/temporal-worker-controller/templates/rbac.yaml
+++ b/helm/temporal-worker-controller/templates/rbac.yaml
@@ -174,6 +174,70 @@ rules:
       - update
   {{- end }}
 ---
+{{- if .Values.rbac.restrictWatchNamespaces }}
+# Namespace-scoped mode: the manager role is bound only within the watched
+# namespaces (RoleBindings below). The two grants that must stay cluster-wide are
+# split into a minimal ClusterRole: namespaces "get" (restricted to the release
+# namespace, for the controller identity-suffix lookup) and subjectaccessreviews
+# "create" (the always-on validating webhook).
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  labels:
+    app.kubernetes.io/component: rbac
+    {{- include "temporal-worker-controller.labels" . | nindent 4 }}
+  name: {{ .Release.Name }}-{{ .Release.Namespace }}-manager-cluster-role
+rules:
+  - apiGroups:
+      - ""
+    resources:
+      - namespaces
+    resourceNames:
+      - {{ .Release.Namespace }}
+    verbs:
+      - get
+  - apiGroups:
+      - authorization.k8s.io
+    resources:
+      - subjectaccessreviews
+    verbs:
+      - create
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRoleBinding
+metadata:
+  labels:
+    app.kubernetes.io/component: rbac
+    {{- include "temporal-worker-controller.labels" . | nindent 4 }}
+  name: {{ .Release.Name }}-{{ .Release.Namespace }}-manager-cluster-rolebinding
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: ClusterRole
+  name: {{ .Release.Name }}-{{ .Release.Namespace }}-manager-cluster-role
+subjects:
+  - kind: ServiceAccount
+    name: {{ .Values.serviceAccount.name | default (printf "%s-service-account" .Release.Name) }}
+    namespace: {{ .Release.Namespace }}
+{{- range .Values.rbac.restrictWatchNamespaces }}
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  labels:
+    app.kubernetes.io/component: rbac
+    {{- include "temporal-worker-controller.labels" $ | nindent 4 }}
+  name: {{ $.Release.Name }}-{{ $.Release.Namespace }}-manager-rolebinding
+  namespace: {{ . }}
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: ClusterRole
+  name: {{ $.Release.Name }}-{{ $.Release.Namespace }}-manager-role
+subjects:
+  - kind: ServiceAccount
+    name: {{ $.Values.serviceAccount.name | default (printf "%s-service-account" $.Release.Name) }}
+    namespace: {{ $.Release.Namespace }}
+{{- end }}
+{{- else }}
 apiVersion: rbac.authorization.k8s.io/v1
 kind: ClusterRoleBinding
 metadata:
@@ -189,6 +253,7 @@ subjects:
   - kind: ServiceAccount
     name: {{ .Values.serviceAccount.name | default (printf "%s-service-account" .Release.Name) }}
     namespace: {{ .Release.Namespace }}
+{{- end }}
 ---
 # permissions for end users to edit connections (new name).
 apiVersion: rbac.authorization.k8s.io/v1
diff --git a/helm/temporal-worker-controller/templates/webhook.yaml b/helm/temporal-worker-controller/templates/webhook.yaml
index 9acd8b74..c159d5c1 100644
--- a/helm/temporal-worker-controller/templates/webhook.yaml
+++ b/helm/temporal-worker-controller/templates/webhook.yaml
@@ -48,6 +48,9 @@ webhooks:
         operations: ["CREATE", "UPDATE", "DELETE"]
         resources: ["workerresourcetemplates"]
     sideEffects: None
+    {{- if .Values.rbac.restrictWatchNamespaces }}
+    {{- include "temporal-worker-controller.webhookNamespaceSelector" . | nindent 4 }}
+    {{- end }}
 {{- if .Values.webhook.enabled }}
 ---
 # ValidatingWebhookConfiguration for WorkerDeployment.
@@ -80,4 +83,7 @@ webhooks:
         operations: ["CREATE", "UPDATE"]
         resources: ["workerdeployments"]
     sideEffects: None
+    {{- if .Values.rbac.restrictWatchNamespaces }}
+    {{- include "temporal-worker-controller.webhookNamespaceSelector" . | nindent 4 }}
+    {{- end }}
 {{- end }}
diff --git a/helm/temporal-worker-controller/values.schema.json b/helm/temporal-worker-controller/values.schema.json
index fab85d20..30001aff 100644
--- a/helm/temporal-worker-controller/values.schema.json
+++ b/helm/temporal-worker-controller/values.schema.json
@@ -109,6 +109,13 @@
         "create": {
           "type": "boolean",
           "description": "Whether to create RBAC resources"
+        },
+        "restrictWatchNamespaces": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          },
+          "description": "Namespaces the controller watches and is granted RBAC in. Empty (the default) watches all namespaces with cluster-wide RBAC; when set, the controller is scoped to these namespaces via per-namespace RoleBindings plus a minimal cluster-scoped role."
         }
       }
     },
diff --git a/helm/temporal-worker-controller/values.yaml b/helm/temporal-worker-controller/values.yaml
index 22466977..d4246c31 100644
--- a/helm/temporal-worker-controller/values.yaml
+++ b/helm/temporal-worker-controller/values.yaml
@@ -40,6 +40,13 @@ priorityClassName: ""
 rbac:
   # Specifies whether RBAC resources should be created
   create: true
+  # restrictWatchNamespaces keeps the namespaces the controller watches and the
+  # namespaces its RBAC grants access to in sync. Empty (the default) watches all
+  # namespaces with cluster-wide RBAC. When set, the controller watches only these
+  # namespaces (via WATCH_NAMESPACES) and is granted the manager role through a
+  # RoleBinding in each listed namespace, plus a minimal cluster-scoped role for the
+  # two grants that cannot be namespaced (namespaces get, subjectaccessreviews create).
+  restrictWatchNamespaces: []
 
 serviceAccount:
   # Specifies whether a ServiceAccount should be created
diff --git a/internal/controller/cache.go b/internal/controller/cache.go
index e0b5730b..bf0a9b1d 100644
--- a/internal/controller/cache.go
+++ b/internal/controller/cache.go
@@ -5,6 +5,8 @@
 package controller
 
 import (
+	"strings"
+
 	"github.com/temporalio/temporal-worker-controller/internal/k8s"
 	appsv1 "k8s.io/api/apps/v1"
 	"k8s.io/apimachinery/pkg/labels"
@@ -19,17 +21,48 @@ import (
 // but controller-runtime still lists, watches, and retains cached Deployment
 // objects before those events reach the controller. Restricting the manager cache
 // prevents unrelated cluster Deployments from growing the controller's memory use.
-func NewCacheOptions() (cache.Options, error) {
+//
+// When watchNamespaces is non-empty the cache (and therefore the controller's
+// watches) is restricted to those namespaces; empty means all namespaces.
+func NewCacheOptions(watchNamespaces []string) (cache.Options, error) {
 	deploymentLabelReq, err := labels.NewRequirement(k8s.WorkerDeploymentNameLabel, selection.Exists, nil)
 	if err != nil {
 		return cache.Options{}, err
 	}
 
-	return cache.Options{
+	opts := cache.Options{
 		ByObject: map[client.Object]cache.ByObject{
 			&appsv1.Deployment{}: {
 				Label: labels.NewSelector().Add(*deploymentLabelReq),
 			},
 		},
-	}, nil
+	}
+
+	if len(watchNamespaces) > 0 {
+		defaultNamespaces := make(map[string]cache.Config, len(watchNamespaces))
+		for _, ns := range watchNamespaces {
+			defaultNamespaces[ns] = cache.Config{}
+		}
+		opts.DefaultNamespaces = defaultNamespaces
+	}
+
+	return opts, nil
+}
+
+// ParseWatchNamespaces splits a comma-separated namespace list (from the
+// --watch-namespaces flag or WATCH_NAMESPACES env var) into a slice, trimming
+// whitespace and dropping empty entries. An empty input returns nil, which
+// NewCacheOptions treats as "watch all namespaces".
+func ParseWatchNamespaces(raw string) []string {
+	if raw == "" {
+		return nil
+	}
+	parts := strings.Split(raw, ",")
+	namespaces := make([]string, 0, len(parts))
+	for _, p := range parts {
+		if ns := strings.TrimSpace(p); ns != "" {
+			namespaces = append(namespaces, ns)
+		}
+	}
+	return namespaces
 }
diff --git a/internal/controller/cache_test.go b/internal/controller/cache_test.go
index df709dd2..8474c291 100644
--- a/internal/controller/cache_test.go
+++ b/internal/controller/cache_test.go
@@ -5,6 +5,7 @@
 package controller
 
 import (
+	"reflect"
 	"testing"
 
 	"github.com/temporalio/temporal-worker-controller/internal/k8s"
@@ -13,7 +14,7 @@ import (
 )
 
 func TestNewCacheOptionsScopesDeploymentsByWorkerLabel(t *testing.T) {
-	opts, err := NewCacheOptions()
+	opts, err := NewCacheOptions(nil)
 	if err != nil {
 		t.Fatalf("NewCacheOptions returned error: %v", err)
 	}
@@ -40,3 +41,53 @@ func TestNewCacheOptionsScopesDeploymentsByWorkerLabel(t *testing.T) {
 		t.Fatal("expected selector not to match unlabeled Deployment")
 	}
 }
+
+func TestNewCacheOptionsScopesToWatchNamespaces(t *testing.T) {
+	opts, err := NewCacheOptions([]string{"ns-a", "ns-b"})
+	if err != nil {
+		t.Fatalf("NewCacheOptions returned error: %v", err)
+	}
+
+	if len(opts.DefaultNamespaces) != 2 {
+		t.Fatalf("expected 2 default namespaces, got %d", len(opts.DefaultNamespaces))
+	}
+	for _, ns := range []string{"ns-a", "ns-b"} {
+		if _, ok := opts.DefaultNamespaces[ns]; !ok {
+			t.Fatalf("expected namespace %q in DefaultNamespaces", ns)
+		}
+	}
+}
+
+func TestNewCacheOptionsWatchesAllNamespacesWhenEmpty(t *testing.T) {
+	opts, err := NewCacheOptions(nil)
+	if err != nil {
+		t.Fatalf("NewCacheOptions returned error: %v", err)
+	}
+
+	if len(opts.DefaultNamespaces) != 0 {
+		t.Fatalf("expected no default namespaces, got %d", len(opts.DefaultNamespaces))
+	}
+}
+
+func TestParseWatchNamespaces(t *testing.T) {
+	tests := []struct {
+		name string
+		raw  string
+		want []string
+	}{
+		{name: "empty returns nil", raw: "", want: nil},
+		{name: "single namespace", raw: "ns-a", want: []string{"ns-a"}},
+		{name: "comma separated", raw: "ns-a,ns-b", want: []string{"ns-a", "ns-b"}},
+		{name: "trims whitespace and drops empties", raw: " ns-a , , ns-b ,", want: []string{"ns-a", "ns-b"}},
+		{name: "separators only returns empty slice", raw: " , , ", want: []string{}},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := ParseWatchNamespaces(tt.raw)
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Fatalf("ParseWatchNamespaces(%q) = %#v, want %#v", tt.raw, got, tt.want)
+			}
+		})
+	}
+}