diff --git a/core/java/android/net/ConnectivityDiagnosticsManager.java b/core/java/android/net/ConnectivityDiagnosticsManager.java
index 6f0a4f9744..aa35852f78 100644
--- a/core/java/android/net/ConnectivityDiagnosticsManager.java
+++ b/core/java/android/net/ConnectivityDiagnosticsManager.java
@@ -659,7 +659,8 @@ public class ConnectivityDiagnosticsManager {
     public abstract static class ConnectivityDiagnosticsCallback {
         /**
          * Called when the platform completes a data connectivity check. This will also be invoked
-         * upon registration with the latest report.
+         * immediately upon registration with the latest report, if a report has already been
+         * generated for this network.
          *
          * <p>The Network specified in the ConnectivityReport may not be active any more when this
          * method is invoked.
diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index d684f0c199..2b5f21a172 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -7855,6 +7855,34 @@ public class ConnectivityService extends IConnectivityManager.Stub
             cb.asBinder().linkToDeath(cbInfo, 0);
         } catch (RemoteException e) {
             cbInfo.binderDied();
+            return;
+        }
+
+        // Once registered, provide ConnectivityReports for matching Networks
+        final List<NetworkAgentInfo> matchingNetworks = new ArrayList<>();
+        synchronized (mNetworkForNetId) {
+            for (int i = 0; i < mNetworkForNetId.size(); i++) {
+                final NetworkAgentInfo nai = mNetworkForNetId.valueAt(i);
+                if (nai.satisfies(nri.request)) {
+                    matchingNetworks.add(nai);
+                }
+            }
+        }
+        for (final NetworkAgentInfo nai : matchingNetworks) {
+            final ConnectivityReport report = nai.getConnectivityReport();
+            if (report == null) {
+                continue;
+            }
+            if (!checkConnectivityDiagnosticsPermissions(
+                    nri.mPid, nri.mUid, nai, cbInfo.mCallingPackageName)) {
+                continue;
+            }
+
+            try {
+                cb.onConnectivityReportAvailable(report);
+            } catch (RemoteException e) {
+                // Exception while sending the ConnectivityReport. Move on to the next network.
+            }
         }
     }
 
@@ -7890,6 +7918,7 @@ public class ConnectivityService extends IConnectivityManager.Stub
                         nai.linkProperties,
                         networkCapabilities,
                         extras);
+        nai.setConnectivityReport(report);
         final List<IConnectivityDiagnosticsCallback> results =
                 getMatchingPermissionedCallbacks(nai);
         for (final IConnectivityDiagnosticsCallback cb : results) {
diff --git a/services/core/java/com/android/server/connectivity/NetworkAgentInfo.java b/services/core/java/com/android/server/connectivity/NetworkAgentInfo.java
index 2f047157d4..d2086138a1 100644
--- a/services/core/java/com/android/server/connectivity/NetworkAgentInfo.java
+++ b/services/core/java/com/android/server/connectivity/NetworkAgentInfo.java
@@ -16,6 +16,7 @@
 
 package com.android.server.connectivity;
 
+import static android.net.ConnectivityDiagnosticsManager.ConnectivityReport;
 import static android.net.NetworkCapabilities.transportNamesOf;
 
 import android.annotation.NonNull;
@@ -243,6 +244,9 @@ public class NetworkAgentInfo implements Comparable<NetworkAgentInfo> {
     // How many of the satisfied requests are of type BACKGROUND_REQUEST.
     private int mNumBackgroundNetworkRequests = 0;
 
+    // The last ConnectivityReport made available for this network.
+    private ConnectivityReport mConnectivityReport;
+
     public final Messenger messenger;
     public final AsyncChannel asyncChannel;
 
@@ -621,6 +625,30 @@ public class NetworkAgentInfo implements Comparable<NetworkAgentInfo> {
         for (LingerTimer timer : mLingerTimers) { pw.println(timer); }
     }
 
+    /**
+     * Sets the most recent ConnectivityReport for this network.
+     *
+     * <p>This should only be called from the ConnectivityService thread.
+     *
+     * @hide
+     */
+    public void setConnectivityReport(@NonNull ConnectivityReport connectivityReport) {
+        mConnectivityReport = connectivityReport;
+    }
+
+    /**
+     * Returns the most recent ConnectivityReport for this network, or null if none have been
+     * reported yet.
+     *
+     * <p>This should only be called from the ConnectivityService thread.
+     *
+     * @hide
+     */
+    @Nullable
+    public ConnectivityReport getConnectivityReport() {
+        return mConnectivityReport;
+    }
+
     // TODO: Print shorter members first and only print the boolean variable which value is true
     // to improve readability.
     public String toString() {
diff --git a/tests/net/java/com/android/server/ConnectivityServiceTest.java b/tests/net/java/com/android/server/ConnectivityServiceTest.java
index 86d8a820e4..50b61fb40f 100644
--- a/tests/net/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/net/java/com/android/server/ConnectivityServiceTest.java
@@ -317,6 +317,8 @@ public class ConnectivityServiceTest {
     private static final String TEST_PACKAGE_NAME = "com.android.test.package";
     private static final String[] EMPTY_STRING_ARRAY = new String[0];
 
+    private static final String INTERFACE_NAME = "interface";
+
     private MockContext mServiceContext;
     private HandlerThread mCsHandlerThread;
     private ConnectivityService mService;
@@ -6915,6 +6917,38 @@ public class ConnectivityServiceTest {
                         mContext.getOpPackageName()));
     }
 
+    @Test
+    public void testRegisterConnectivityDiagnosticsCallbackCallsOnConnectivityReport()
+            throws Exception {
+        // Set up the Network, which leads to a ConnectivityReport being cached for the network.
+        final TestNetworkCallback callback = new TestNetworkCallback();
+        mCm.registerDefaultNetworkCallback(callback);
+        final LinkProperties linkProperties = new LinkProperties();
+        linkProperties.setInterfaceName(INTERFACE_NAME);
+        mCellNetworkAgent = new TestNetworkAgentWrapper(TRANSPORT_CELLULAR, linkProperties);
+        mCellNetworkAgent.connect(true);
+        callback.expectAvailableThenValidatedCallbacks(mCellNetworkAgent);
+        callback.assertNoCallback();
+
+        final NetworkRequest request = new NetworkRequest.Builder().build();
+        when(mConnectivityDiagnosticsCallback.asBinder()).thenReturn(mIBinder);
+
+        mServiceContext.setPermission(
+                android.Manifest.permission.NETWORK_STACK, PERMISSION_GRANTED);
+
+        mService.registerConnectivityDiagnosticsCallback(
+                mConnectivityDiagnosticsCallback, request, mContext.getPackageName());
+
+        // Block until all other events are done processing.
+        HandlerUtilsKt.waitForIdle(mCsHandlerThread, TIMEOUT_MS);
+
+        verify(mConnectivityDiagnosticsCallback)
+                .onConnectivityReportAvailable(argThat(report -> {
+                    return INTERFACE_NAME.equals(report.getLinkProperties().getInterfaceName())
+                            && report.getNetworkCapabilities().hasTransport(TRANSPORT_CELLULAR);
+                }));
+    }
+
     private void setUpConnectivityDiagnosticsCallback() throws Exception {
         final NetworkRequest request = new NetworkRequest.Builder().build();
         when(mConnectivityDiagnosticsCallback.asBinder()).thenReturn(mIBinder);