diff --git a/src/com/android/settings/notification/modes/ZenSettingsObserver.java b/src/com/android/settings/notification/modes/ZenSettingsObserver.java
index a853646fd94..0f22d7de341 100644
--- a/src/com/android/settings/notification/modes/ZenSettingsObserver.java
+++ b/src/com/android/settings/notification/modes/ZenSettingsObserver.java
@@ -16,6 +16,7 @@
 
 package com.android.settings.notification.modes;
 
+import android.app.Flags;
 import android.content.Context;
 import android.database.ContentObserver;
 import android.net.Uri;
@@ -42,13 +43,17 @@ class ZenSettingsObserver extends ContentObserver {
     }
 
     void register() {
-        mContext.getContentResolver().registerContentObserver(ZEN_MODE_URI, false, this);
-        mContext.getContentResolver().registerContentObserver(ZEN_MODE_CONFIG_ETAG_URI, false,
-                this);
+        if (Flags.modesApi() && Flags.modesUi()) {
+            mContext.getContentResolver().registerContentObserver(ZEN_MODE_URI, false, this);
+            mContext.getContentResolver().registerContentObserver(ZEN_MODE_CONFIG_ETAG_URI, false,
+                    this);
+        }
     }
 
     void unregister() {
-        mContext.getContentResolver().unregisterContentObserver(this);
+        if (Flags.modesApi() && Flags.modesUi()) {
+            mContext.getContentResolver().unregisterContentObserver(this);
+        }
     }
 
     void setOnChangeListener(@Nullable Runnable callback) {
diff --git a/tests/robotests/src/com/android/settings/notification/modes/ZenSettingsObserverTest.java b/tests/robotests/src/com/android/settings/notification/modes/ZenSettingsObserverTest.java
new file mode 100644
index 00000000000..7fd47d9d9c1
--- /dev/null
+++ b/tests/robotests/src/com/android/settings/notification/modes/ZenSettingsObserverTest.java
@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.notification.modes;
+
+import static android.provider.Settings.Global.ZEN_MODE_CONFIG_ETAG;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.robolectric.Shadows.shadowOf;
+
+import android.app.Flags;
+import android.content.Context;
+import android.database.ContentObserver;
+import android.net.Uri;
+import android.platform.test.annotations.DisableFlags;
+import android.platform.test.annotations.EnableFlags;
+import android.platform.test.flag.junit.SetFlagsRule;
+import android.provider.Settings;
+
+import androidx.test.core.app.ApplicationProvider;
+
+import com.google.common.collect.ImmutableList;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.shadows.ShadowLooper;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+@RunWith(RobolectricTestRunner.class)
+public class ZenSettingsObserverTest {
+
+    @Rule
+    public final SetFlagsRule mSetFlagsRule = new SetFlagsRule();
+
+    private static final Uri SETTINGS_URI = Settings.Global.getUriFor(
+            ZEN_MODE_CONFIG_ETAG);
+
+    private Context mContext;
+    private ZenSettingsObserver mObserver;
+
+    @Before
+    public void setUp() {
+        mContext = ApplicationProvider.getApplicationContext();
+        mObserver = new ZenSettingsObserver(mContext);
+    }
+
+    @Test
+    @EnableFlags(Flags.FLAG_MODES_UI)
+    public void register_withFlagEnabled_registersAndCallsBack() {
+        AtomicInteger someValue = new AtomicInteger();
+        mObserver.setOnChangeListener(someValue::incrementAndGet);
+        assertThat(getSettingsContentObservers()).isEmpty();
+
+        mObserver.register();
+        assertThat(getSettingsContentObservers()).hasSize(1);
+
+        getSettingsContentObservers().forEach(o -> o.dispatchChange(false, SETTINGS_URI));
+        ShadowLooper.idleMainLooper();
+        assertThat(someValue.get()).isEqualTo(1);
+
+        mObserver.unregister();
+        assertThat(getSettingsContentObservers()).isEmpty();
+    }
+
+    @Test
+    @DisableFlags(Flags.FLAG_MODES_UI)
+    public void register_withFlagDisabled_doesNotRegister() {
+        mObserver.register();
+        assertThat(getSettingsContentObservers()).isEmpty();
+        mObserver.unregister();
+        assertThat(getSettingsContentObservers()).isEmpty();
+    }
+
+    private ImmutableList<ContentObserver> getSettingsContentObservers() {
+        return ImmutableList.copyOf(
+                shadowOf(mContext.getContentResolver())
+                        .getContentObservers(SETTINGS_URI));
+    }
+}