diff --git a/res/values/evolution_strings.xml b/res/values/evolution_strings.xml
index d00d968c24e..80f16138cfd 100644
--- a/res/values/evolution_strings.xml
+++ b/res/values/evolution_strings.xml
@@ -157,4 +157,8 @@
         <item quantity="other">Up to <xliff:g id="device_num">%1$d</xliff:g> devices can connect to this hotspot</item>
         <item quantity="one">Up to <xliff:g id="device_num">%1$d</xliff:g> device can connect to this hotspot</item>
     </plurals>
+
+    <!-- Smart 5G -->
+    <string name="smart_5g_title">Smart 5G</string>
+    <string name="smart_5g_summary">Automatically switch between 5G and 4G to reduce battery consumption</string>
 </resources>
diff --git a/res/xml/mobile_network_settings.xml b/res/xml/mobile_network_settings.xml
index 72d03bab62c..d40f85f50ec 100644
--- a/res/xml/mobile_network_settings.xml
+++ b/res/xml/mobile_network_settings.xml
@@ -295,6 +295,13 @@
                 android:key="choose_network_key"
                 android:title="@string/choose_network_title"
                 settings:controller="com.android.settings.network.telephony.gsm.OpenNetworkSelectPagePreferenceController"/>
+
+            <SwitchPreferenceCompat
+                android:key="smart_5g"
+                android:title="@string/smart_5g_title"
+                android:persistent="false"
+                android:summary="@string/smart_5g_summary"
+                settings:controller="com.android.settings.network.telephony.Smart5gPreferenceController"/>
         </PreferenceCategory>
 
         <!--We want separate APN setting from reset of settings because we want user to change it with caution-->
diff --git a/src/com/android/settings/network/telephony/MobileNetworkSettings.java b/src/com/android/settings/network/telephony/MobileNetworkSettings.java
index 756206751ec..a8ed8e2f63a 100644
--- a/src/com/android/settings/network/telephony/MobileNetworkSettings.java
+++ b/src/com/android/settings/network/telephony/MobileNetworkSettings.java
@@ -330,6 +330,7 @@ public class MobileNetworkSettings extends AbstractMobileNetworkSettings impleme
                 .addListener(videoCallingPreferenceController);
         use(ContactDiscoveryPreferenceController.class).init(getParentFragmentManager(), mSubId);
         use(NrAdvancedCallingPreferenceController.class).init(mSubId);
+        use(Smart5gPreferenceController.class).init(mSubId);
         use(TransferEsimPreferenceController.class).init(mSubId, mSubscriptionInfoEntity);
         use(ForceLteCaPreferenceController.class).init(mSubId);
         final ConvertToEsimPreferenceController convertToEsimPreferenceController =
diff --git a/src/com/android/settings/network/telephony/Smart5gPreferenceController.java b/src/com/android/settings/network/telephony/Smart5gPreferenceController.java
new file mode 100644
index 00000000000..cfff7a66bb1
--- /dev/null
+++ b/src/com/android/settings/network/telephony/Smart5gPreferenceController.java
@@ -0,0 +1,173 @@
+/*
+ * Copyright (C) 2021 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.network.telephony;
+
+import static android.provider.Settings.System.SMART_5G;
+
+import android.content.Context;
+import android.os.UserHandle;
+import android.provider.Settings;
+import android.telephony.SubscriptionManager;
+import android.telephony.TelephonyCallback;
+import android.telephony.TelephonyManager;
+import android.util.Log;
+
+import androidx.preference.Preference;
+import androidx.preference.PreferenceScreen;
+import androidx.preference.SwitchPreferenceCompat;
+import androidx.preference.TwoStatePreference;
+
+import com.android.settingslib.core.lifecycle.LifecycleObserver;
+import com.android.settingslib.core.lifecycle.events.OnStart;
+import com.android.settingslib.core.lifecycle.events.OnStop;
+
+/**
+ * Preference controller for Smart 5G
+ */
+public class Smart5gPreferenceController extends TelephonyTogglePreferenceController
+        implements LifecycleObserver, OnStart, OnStop {
+
+    private static final String TAG = "Smart5gPreferenceController";
+
+    Preference mPreference;
+    private TelephonyManager mTelephonyManager;
+    private PhoneCallStateTelephonyCallback mTelephonyCallback;
+    private boolean mHas5gCapability = false;
+    private Integer mCallState = TelephonyManager.CALL_STATE_IDLE;
+
+    public Smart5gPreferenceController(Context context, String key) {
+        super(context, key);
+        mTelephonyManager = context.getSystemService(TelephonyManager.class);
+    }
+
+    /**
+     * Initialize this PreferenceController.
+     * @param subId The subscription Id.
+     * @return This PreferenceController.
+     */
+    public Smart5gPreferenceController init(int subId) {
+        Log.d(TAG, "init: subId=" + subId);
+        if (mTelephonyCallback == null) {
+            mTelephonyCallback = new PhoneCallStateTelephonyCallback();
+        }
+
+        mSubId = subId;
+
+        if (mTelephonyManager == null) {
+            mTelephonyManager = mContext.getSystemService(TelephonyManager.class);
+        }
+        if (SubscriptionManager.isValidSubscriptionId(subId)) {
+            mTelephonyManager = mTelephonyManager.createForSubscriptionId(subId);
+        }
+        long supportedRadioBitmask = mTelephonyManager.getSupportedRadioAccessFamily();
+        mHas5gCapability =
+                (supportedRadioBitmask & TelephonyManager.NETWORK_TYPE_BITMASK_NR) > 0;
+
+        Log.d(TAG, "mHas5gCapability: " + mHas5gCapability);
+        return this;
+    }
+
+    @Override
+    public int getAvailabilityStatus(int subId) {
+        init(subId);
+        return mHas5gCapability ? AVAILABLE : CONDITIONALLY_UNAVAILABLE;
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        mPreference = screen.findPreference(getPreferenceKey());
+    }
+
+    @Override
+    public void onStart() {
+        if (mTelephonyCallback == null) {
+            return;
+        }
+        mTelephonyCallback.register(mTelephonyManager);
+    }
+
+    @Override
+    public void onStop() {
+        if (mTelephonyCallback == null) {
+            return;
+        }
+        mTelephonyCallback.unregister();
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        super.updateState(preference);
+        if (preference == null) {
+            return;
+        }
+        final TwoStatePreference switchPreference = (TwoStatePreference) preference;
+        switchPreference.setEnabled(isUserControlAllowed());
+    }
+
+    @Override
+    public boolean setChecked(boolean isChecked) {
+        if (!SubscriptionManager.isValidSubscriptionId(mSubId)) {
+            return false;
+        }
+        return Settings.System.putIntForUser(mContext.getContentResolver(),
+                SMART_5G + mSubId, isChecked ? 1 : 0, UserHandle.USER_CURRENT);
+    }
+
+    @Override
+    public boolean isChecked() {
+        return Settings.System.getIntForUser(mContext.getContentResolver(),
+                SMART_5G + mSubId, 0, UserHandle.USER_CURRENT) == 1;
+    }
+
+    protected boolean isCallStateIdle() {
+        return (mCallState != null) && (mCallState == TelephonyManager.CALL_STATE_IDLE);
+    }
+
+    private boolean isUserControlAllowed() {
+        return isCallStateIdle();
+    }
+
+    private class PhoneCallStateTelephonyCallback extends TelephonyCallback implements
+            TelephonyCallback.CallStateListener {
+
+        private TelephonyManager mLocalTelephonyManager;
+
+        @Override
+        public void onCallStateChanged(int state) {
+            mCallState = state;
+            updateState(mPreference);
+        }
+
+        public void register(TelephonyManager telephonyManager) {
+            mLocalTelephonyManager = telephonyManager;
+
+            // assign current call state so that it helps to show correct preference state even
+            // before first onCallStateChanged() by initial registration.
+            mCallState = mLocalTelephonyManager.getCallState();
+            mLocalTelephonyManager.registerTelephonyCallback(
+                    mContext.getMainExecutor(), mTelephonyCallback);
+        }
+
+        public void unregister() {
+            mCallState = null;
+            if (mLocalTelephonyManager != null) {
+                mLocalTelephonyManager.unregisterTelephonyCallback(this);
+            }
+        }
+    }
+}