diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index aa1648f..3771bbc 100644
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -617,6 +617,11 @@
     private static final int EVENT_UNREGISTER_NETWORK_OFFER = 53;
 
     /**
+     * Used internally when MOBILE_DATA_PREFERRED_UIDS setting changed.
+     */
+    private static final int EVENT_MOBILE_DATA_PREFERRED_UIDS_CHANGED = 54;
+
+    /**
      * Argument for {@link #EVENT_PROVISIONING_NOTIFICATION} to indicate that the notification
      * should be shown.
      */
@@ -1460,6 +1465,11 @@
         mHandler.sendEmptyMessage(EVENT_PRIVATE_DNS_SETTINGS_CHANGED);
     }
 
+    @VisibleForTesting
+    void updateMobileDataPreferredUids() {
+        mHandler.sendEmptyMessage(EVENT_MOBILE_DATA_PREFERRED_UIDS_CHANGED);
+    }
+
     private void handleAlwaysOnNetworkRequest(NetworkRequest networkRequest, int id) {
         final boolean enable = mContext.getResources().getBoolean(id);
         handleAlwaysOnNetworkRequest(networkRequest, enable);
@@ -1504,6 +1514,8 @@
                 vehicleAlwaysRequested || legacyAlwaysRequested);
     }
 
+    // Note that registering observer for setting do not get initial callback when registering,
+    // callers might have self-initialization to update status if need.
     private void registerSettingsCallbacks() {
         // Watch for global HTTP proxy changes.
         mSettingsObserver.observe(
@@ -1519,6 +1531,11 @@
         mSettingsObserver.observe(
                 Settings.Global.getUriFor(ConnectivitySettingsManager.WIFI_ALWAYS_REQUESTED),
                 EVENT_CONFIGURE_ALWAYS_ON_NETWORKS);
+
+        // Watch for mobile data preferred uids changes.
+        mSettingsObserver.observe(
+                Settings.Secure.getUriFor(ConnectivitySettingsManager.MOBILE_DATA_PREFERRED_UIDS),
+                EVENT_MOBILE_DATA_PREFERRED_UIDS_CHANGED);
     }
 
     private void registerPrivateDnsSettingsCallbacks() {
@@ -2717,6 +2734,13 @@
 
         // Create network requests for always-on networks.
         mHandler.sendMessage(mHandler.obtainMessage(EVENT_CONFIGURE_ALWAYS_ON_NETWORKS));
+
+        // Update mobile data preference if necessary.
+        // Note that empty uid list can be skip here only because no uid rules applied before system
+        // ready. Normally, the empty uid list means to clear the uids rules on netd.
+        if (!ConnectivitySettingsManager.getMobileDataPreferredUids(mContext).isEmpty()) {
+            updateMobileDataPreferredUids();
+        }
     }
 
     /**
@@ -4801,6 +4825,9 @@
                 case EVENT_REPORT_NETWORK_ACTIVITY:
                     mNetworkActivityTracker.handleReportNetworkActivity();
                     break;
+                case EVENT_MOBILE_DATA_PREFERRED_UIDS_CHANGED:
+                    handleMobileDataPreferredUidsChanged();
+                    break;
             }
         }
     }
@@ -5605,7 +5632,7 @@
          * Get the list of UIDs this nri applies to.
          */
         @NonNull
-        private Set<UidRange> getUids() {
+        Set<UidRange> getUids() {
             // networkCapabilities.getUids() returns a defensive copy.
             // multilayer requests will all have the same uids so return the first one.
             final Set<UidRange> uids = mRequests.get(0).networkCapabilities.getUidRanges();
@@ -6319,6 +6346,11 @@
     @NonNull
     private ProfileNetworkPreferences mProfileNetworkPreferences = new ProfileNetworkPreferences();
 
+    // A set of UIDs that should use mobile data preferentially if available. This object follows
+    // the same threading rules as the OEM network preferences above.
+    @NonNull
+    private Set<Integer> mMobileDataPreferredUids = new ArraySet<>();
+
     // OemNetworkPreferences activity String log entries.
     private static final int MAX_OEM_NETWORK_PREFERENCE_LOGS = 20;
     @NonNull
@@ -9686,7 +9718,8 @@
         // safe - it's just possible the value is slightly outdated. For the final check,
         // see #handleSetProfileNetworkPreference. But if this can be caught here it is a
         // lot easier to understand, so opportunistically check it.
-        if (!mOemNetworkPreferences.isEmpty()) {
+        // TODO: Have a priority for each preference.
+        if (!mOemNetworkPreferences.isEmpty() || !mMobileDataPreferredUids.isEmpty()) {
             throwConcurrentPreferenceException();
         }
         final NetworkCapabilities nc;
@@ -9745,7 +9778,8 @@
         // The binder call has already checked this, but as mOemNetworkPreferences is only
         // touched on the handler thread, it's theoretically not impossible that it has changed
         // since.
-        if (!mOemNetworkPreferences.isEmpty()) {
+        // TODO: Have a priority for each preference.
+        if (!mOemNetworkPreferences.isEmpty() || !mMobileDataPreferredUids.isEmpty()) {
             // This may happen on a device with an OEM preference set when a user is removed.
             // In this case, it's safe to ignore. In particular this happens in the tests.
             loge("handleSetProfileNetworkPreference, but OEM network preferences not empty");
@@ -9774,6 +9808,56 @@
         }
     }
 
+    @VisibleForTesting
+    @NonNull
+    ArraySet<NetworkRequestInfo> createNrisFromMobileDataPreferredUids(
+            @NonNull final Set<Integer> uids) {
+        final ArraySet<NetworkRequestInfo> nris = new ArraySet<>();
+        if (uids.size() == 0) {
+            // Should not create NetworkRequestInfo if no preferences. Without uid range in
+            // NetworkRequestInfo, makeDefaultForApps() would treat it as a illegal NRI.
+            if (DBG) log("Don't create NetworkRequestInfo because no preferences");
+            return nris;
+        }
+
+        final List<NetworkRequest> requests = new ArrayList<>();
+        // The NRI should be comprised of two layers:
+        // - The request for the mobile network preferred.
+        // - The request for the default network, for fallback.
+        requests.add(createDefaultInternetRequestForTransport(
+                TRANSPORT_CELLULAR, NetworkRequest.Type.LISTEN));
+        requests.add(createDefaultInternetRequestForTransport(
+                TYPE_NONE, NetworkRequest.Type.TRACK_DEFAULT));
+        final Set<UidRange> ranges = new ArraySet<>();
+        for (final int uid : uids) {
+            ranges.add(new UidRange(uid, uid));
+        }
+        setNetworkRequestUids(requests, ranges);
+        nris.add(new NetworkRequestInfo(Process.myUid(), requests));
+        return nris;
+    }
+
+    private void handleMobileDataPreferredUidsChanged() {
+        // Ignore update preference because it's not clear what preference should win in case both
+        // apply to the same app.
+        // TODO: Have a priority for each preference.
+        if (!mOemNetworkPreferences.isEmpty() || !mProfileNetworkPreferences.isEmpty()) {
+            loge("Ignore mobile data preference change because other preferences are not empty");
+            return;
+        }
+
+        mMobileDataPreferredUids = ConnectivitySettingsManager.getMobileDataPreferredUids(mContext);
+        mSystemNetworkRequestCounter.transact(
+                mDeps.getCallingUid(), 1 /* numOfNewRequests */,
+                () -> {
+                    final ArraySet<NetworkRequestInfo> nris =
+                            createNrisFromMobileDataPreferredUids(mMobileDataPreferredUids);
+                    replaceDefaultNetworkRequestsForPreference(nris);
+                });
+        // Finally, rematch.
+        rematchAllNetworksAndRequests();
+    }
+
     private void enforceAutomotiveDevice() {
         final boolean isAutomotiveDevice =
                 mContext.getPackageManager().hasSystemFeature(PackageManager.FEATURE_AUTOMOTIVE);
@@ -9803,7 +9887,8 @@
         enforceAutomotiveDevice();
         enforceOemNetworkPreferencesPermission();
 
-        if (!mProfileNetworkPreferences.isEmpty()) {
+        // TODO: Have a priority for each preference.
+        if (!mProfileNetworkPreferences.isEmpty() || !mMobileDataPreferredUids.isEmpty()) {
             // Strictly speaking, mProfileNetworkPreferences should only be touched on the
             // handler thread. However it is an immutable object, so reading the reference is
             // safe - it's just possible the value is slightly outdated. For the final check,
@@ -9841,7 +9926,8 @@
         // The binder call has already checked this, but as mOemNetworkPreferences is only
         // touched on the handler thread, it's theoretically not impossible that it has changed
         // since.
-        if (!mProfileNetworkPreferences.isEmpty()) {
+        // TODO: Have a priority for each preference.
+        if (!mProfileNetworkPreferences.isEmpty() || !mMobileDataPreferredUids.isEmpty()) {
             logwtf("handleSetOemPreference, but per-profile network preferences not empty");
             return;
         }
diff --git a/tests/unit/java/com/android/server/ConnectivityServiceTest.java b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
index 04e63fc..0d3cd61 100644
--- a/tests/unit/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
@@ -299,7 +299,9 @@
 import com.android.internal.util.test.BroadcastInterceptingContext;
 import com.android.internal.util.test.FakeSettingsProvider;
 import com.android.net.module.util.ArrayTrackRecord;
+import com.android.net.module.util.CollectionUtils;
 import com.android.server.ConnectivityService.ConnectivityDiagnosticsCallbackInfo;
+import com.android.server.ConnectivityService.NetworkRequestInfo;
 import com.android.server.connectivity.ConnectivityConstants;
 import com.android.server.connectivity.MockableSystemProperties;
 import com.android.server.connectivity.Nat464Xlat;
@@ -415,6 +417,7 @@
     private static final String VPN_IFNAME = "tun10042";
     private static final String TEST_PACKAGE_NAME = "com.android.test.package";
     private static final int TEST_PACKAGE_UID = 123;
+    private static final int TEST_PACKAGE_UID2 = 321;
     private static final String ALWAYS_ON_PACKAGE = "com.android.test.alwaysonvpn";
 
     private static final String INTERFACE_NAME = "interface";
@@ -1170,6 +1173,10 @@
         return ranges;
     }
 
+    private Set<UidRange> uidRangesForUids(Collection<Integer> uids) {
+        return uidRangesForUids(CollectionUtils.toIntArray(uids));
+    }
+
     private static Looper startHandlerThreadAndReturnLooper() {
         final HandlerThread handlerThread = new HandlerThread("MockVpnThread");
         handlerThread.start();
@@ -1536,6 +1543,8 @@
     private static final UserInfo PRIMARY_USER_INFO = new UserInfo(PRIMARY_USER, "",
             UserInfo.FLAG_PRIMARY);
     private static final UserHandle PRIMARY_USER_HANDLE = new UserHandle(PRIMARY_USER);
+    private static final int SECONDARY_USER = 10;
+    private static final UserHandle SECONDARY_USER_HANDLE = new UserHandle(SECONDARY_USER);
 
     private static final int RESTRICTED_USER = 1;
     private static final UserInfo RESTRICTED_USER_INFO = new UserInfo(RESTRICTED_USER, "",
@@ -10050,7 +10059,7 @@
         mCm.registerNetworkCallback(cellRequest, cellNetworkCallback);
         waitForIdle();
 
-        final ConnectivityService.NetworkRequestInfo[] nriOutput = mService.requestsSortedById();
+        final NetworkRequestInfo[] nriOutput = mService.requestsSortedById();
 
         assertTrue(nriOutput.length > 1);
         for (int i = 0; i < nriOutput.length - 1; i++) {
@@ -10333,8 +10342,7 @@
                 .thenReturn(hasFeature);
     }
 
-    private Range<Integer> getNriFirstUidRange(
-            @NonNull final ConnectivityService.NetworkRequestInfo nri) {
+    private Range<Integer> getNriFirstUidRange(@NonNull final NetworkRequestInfo nri) {
         return nri.mRequests.get(0).networkCapabilities.getUids().iterator().next();
     }
 
@@ -10373,7 +10381,7 @@
                 OEM_NETWORK_PREFERENCE_OEM_PAID;
 
         // Act on OemNetworkRequestFactory.createNrisFromOemNetworkPreferences()
-        final ArraySet<ConnectivityService.NetworkRequestInfo> nris =
+        final ArraySet<NetworkRequestInfo> nris =
                 mService.new OemNetworkRequestFactory()
                         .createNrisFromOemNetworkPreferences(
                                 createDefaultOemNetworkPreferences(prefToTest));
@@ -10402,7 +10410,7 @@
                 OEM_NETWORK_PREFERENCE_OEM_PAID_NO_FALLBACK;
 
         // Act on OemNetworkRequestFactory.createNrisFromOemNetworkPreferences()
-        final ArraySet<ConnectivityService.NetworkRequestInfo> nris =
+        final ArraySet<NetworkRequestInfo> nris =
                 mService.new OemNetworkRequestFactory()
                         .createNrisFromOemNetworkPreferences(
                                 createDefaultOemNetworkPreferences(prefToTest));
@@ -10428,7 +10436,7 @@
                 OEM_NETWORK_PREFERENCE_OEM_PAID_ONLY;
 
         // Act on OemNetworkRequestFactory.createNrisFromOemNetworkPreferences()
-        final ArraySet<ConnectivityService.NetworkRequestInfo> nris =
+        final ArraySet<NetworkRequestInfo> nris =
                 mService.new OemNetworkRequestFactory()
                         .createNrisFromOemNetworkPreferences(
                                 createDefaultOemNetworkPreferences(prefToTest));
@@ -10451,7 +10459,7 @@
                 OEM_NETWORK_PREFERENCE_OEM_PRIVATE_ONLY;
 
         // Act on OemNetworkRequestFactory.createNrisFromOemNetworkPreferences()
-        final ArraySet<ConnectivityService.NetworkRequestInfo> nris =
+        final ArraySet<NetworkRequestInfo> nris =
                 mService.new OemNetworkRequestFactory()
                         .createNrisFromOemNetworkPreferences(
                                 createDefaultOemNetworkPreferences(prefToTest));
@@ -10484,7 +10492,7 @@
                 .build();
 
         // Act on OemNetworkRequestFactory.createNrisFromOemNetworkPreferences()
-        final ArraySet<ConnectivityService.NetworkRequestInfo> nris =
+        final ArraySet<NetworkRequestInfo> nris =
                 mService.new OemNetworkRequestFactory().createNrisFromOemNetworkPreferences(pref);
 
         assertNotNull(nris);
@@ -10509,7 +10517,7 @@
                 .build();
 
         // Act on OemNetworkRequestFactory.createNrisFromOemNetworkPreferences()
-        final List<ConnectivityService.NetworkRequestInfo> nris =
+        final List<NetworkRequestInfo> nris =
                 new ArrayList<>(
                         mService.new OemNetworkRequestFactory().createNrisFromOemNetworkPreferences(
                                 pref));
@@ -10541,7 +10549,7 @@
                 .build();
 
         // Act on OemNetworkRequestFactory.createNrisFromOemNetworkPreferences()
-        final List<ConnectivityService.NetworkRequestInfo> nris =
+        final List<NetworkRequestInfo> nris =
                 new ArrayList<>(
                         mService.new OemNetworkRequestFactory().createNrisFromOemNetworkPreferences(
                                 pref));
@@ -10583,7 +10591,7 @@
                 .build();
 
         // Act on OemNetworkRequestFactory.createNrisFromOemNetworkPreferences()
-        final ArraySet<ConnectivityService.NetworkRequestInfo> nris =
+        final ArraySet<NetworkRequestInfo> nris =
                 mService.new OemNetworkRequestFactory().createNrisFromOemNetworkPreferences(pref);
 
         assertEquals(expectedNumOfNris, nris.size());
@@ -10676,8 +10684,7 @@
         // each time to confirm it doesn't change under test.
         final int expectedDefaultNetworkRequestsSize = 2;
         assertEquals(expectedDefaultNetworkRequestsSize, mService.mDefaultNetworkRequests.size());
-        for (final ConnectivityService.NetworkRequestInfo defaultRequest
-                : mService.mDefaultNetworkRequests) {
+        for (final NetworkRequestInfo defaultRequest : mService.mDefaultNetworkRequests) {
             final Network defaultNetwork = defaultRequest.getSatisfier() == null
                     ? null : defaultRequest.getSatisfier().network();
             // If this is the default request.
@@ -12506,4 +12513,73 @@
             }
         }
     }
+
+    private void assertCreateNrisFromMobileDataPreferredUids(Set<Integer> uids) {
+        final Set<NetworkRequestInfo> nris =
+                mService.createNrisFromMobileDataPreferredUids(uids);
+        final NetworkRequestInfo nri = nris.iterator().next();
+        // Verify that one NRI is created with multilayer requests. Because one NRI can contain
+        // multiple uid ranges, so it only need create one NRI here.
+        assertEquals(1, nris.size());
+        assertTrue(nri.isMultilayerRequest());
+        assertEquals(nri.getUids(), uidRangesForUids(uids));
+    }
+
+    /**
+     * Test createNrisFromMobileDataPreferredUids returns correct NetworkRequestInfo.
+     */
+    @Test
+    public void testCreateNrisFromMobileDataPreferredUids() {
+        // Verify that empty uid set should not create any NRI for it.
+        final Set<NetworkRequestInfo> nrisNoUid =
+                mService.createNrisFromMobileDataPreferredUids(new ArraySet<>());
+        assertEquals(0, nrisNoUid.size());
+
+        final int uid1 = PRIMARY_USER_HANDLE.getUid(TEST_PACKAGE_UID);
+        final int uid2 = PRIMARY_USER_HANDLE.getUid(TEST_PACKAGE_UID2);
+        final int uid3 = SECONDARY_USER_HANDLE.getUid(TEST_PACKAGE_UID);
+        assertCreateNrisFromMobileDataPreferredUids(Set.of(uid1));
+        assertCreateNrisFromMobileDataPreferredUids(Set.of(uid1, uid3));
+        assertCreateNrisFromMobileDataPreferredUids(Set.of(uid1, uid2));
+    }
+
+    private void setAndUpdateMobileDataPreferredUids(Set<Integer> uids) {
+        ConnectivitySettingsManager.setMobileDataPreferredUids(mServiceContext, uids);
+        mService.updateMobileDataPreferredUids();
+        waitForIdle();
+    }
+
+    /**
+     * Test that MOBILE_DATA_PREFERRED_UIDS changes will send correct net id and uid ranges to netd.
+     */
+    @Test
+    public void testMobileDataPreferredUidsChanged() throws Exception {
+        final InOrder inorder = inOrder(mMockNetd);
+        mCellNetworkAgent = new TestNetworkAgentWrapper(TRANSPORT_CELLULAR);
+        mCellNetworkAgent.connect(true);
+        waitForIdle();
+
+        final int cellNetId = mCellNetworkAgent.getNetwork().netId;
+        inorder.verify(mMockNetd, times(1)).networkCreate(nativeNetworkConfigPhysical(
+                cellNetId, INetd.PERMISSION_NONE));
+
+        // Initial mobile data preferred uids status.
+        setAndUpdateMobileDataPreferredUids(Set.of());
+        inorder.verify(mMockNetd, never()).networkAddUidRanges(anyInt(), any());
+        inorder.verify(mMockNetd, never()).networkRemoveUidRanges(anyInt(), any());
+
+        final Set<Integer> uids1 = Set.of(PRIMARY_USER_HANDLE.getUid(TEST_PACKAGE_UID));
+        final UidRangeParcel[] uidRanges1 = toUidRangeStableParcels(uidRangesForUids(uids1));
+        setAndUpdateMobileDataPreferredUids(uids1);
+        inorder.verify(mMockNetd, times(1)).networkAddUidRanges(cellNetId, uidRanges1);
+        inorder.verify(mMockNetd, never()).networkRemoveUidRanges(anyInt(), any());
+
+        final Set<Integer> uids2 = Set.of(PRIMARY_USER_HANDLE.getUid(TEST_PACKAGE_UID),
+                PRIMARY_USER_HANDLE.getUid(TEST_PACKAGE_UID2),
+                SECONDARY_USER_HANDLE.getUid(TEST_PACKAGE_UID));
+        final UidRangeParcel[] uidRanges2 = toUidRangeStableParcels(uidRangesForUids(uids2));
+        setAndUpdateMobileDataPreferredUids(uids2);
+        inorder.verify(mMockNetd, times(1)).networkRemoveUidRanges(cellNetId, uidRanges1);
+        inorder.verify(mMockNetd, times(1)).networkAddUidRanges(cellNetId, uidRanges2);
+    }
 }