diff --git a/quic/api/QuicTransportFunctions.cpp b/quic/api/QuicTransportFunctions.cpp
index a35f3134b..2e2775e7a 100644
--- a/quic/api/QuicTransportFunctions.cpp
+++ b/quic/api/QuicTransportFunctions.cpp
@@ -2063,4 +2063,16 @@ void maybeAddPacketMark(
   }
 }
 
+void maybeScheduleAckForCongestionFeedback(
+    const ReceivedUdpPacket& receivedPacket,
+    AckState& ackState) {
+  // If the packet was marked as having encountered congestion, send an ACK
+  // immediately to ensure timely response from the peer.
+  // Note that the tosValue will be populated only if the enableEcnOnEgress
+  // transport setting is enabled.
+  if ((receivedPacket.tosValue & 0b11) == 0b11) {
+    ackState.needsToSendAckImmediately = true;
+  }
+}
+
 } // namespace quic
diff --git a/quic/api/QuicTransportFunctions.h b/quic/api/QuicTransportFunctions.h
index 2d177065e..921871759 100644
--- a/quic/api/QuicTransportFunctions.h
+++ b/quic/api/QuicTransportFunctions.h
@@ -343,5 +343,7 @@ void maybeVerifyPendingKeyUpdate(
 void maybeAddPacketMark(
     QuicConnectionStateBase& conn,
     OutstandingPacketWrapper& op);
-
+void maybeScheduleAckForCongestionFeedback(
+    const ReceivedUdpPacket& receivedPacket,
+    AckState& ackState);
 } // namespace quic
diff --git a/quic/client/QuicClientTransport.cpp b/quic/client/QuicClientTransport.cpp
index 21fbe1750..a0f8e8c79 100644
--- a/quic/client/QuicClientTransport.cpp
+++ b/quic/client/QuicClientTransport.cpp
@@ -655,6 +655,7 @@ void QuicClientTransport::processUdpPacketData(
     handshakeConfirmed(*conn_);
   }
 
+  maybeScheduleAckForCongestionFeedback(udpPacket, ackState);
   maybeHandleIncomingKeyUpdate(*conn_);
 
   // Try reading bytes off of crypto, and performing a handshake.
diff --git a/quic/server/state/ServerStateMachine.cpp b/quic/server/state/ServerStateMachine.cpp
index c918b00bc..ac485089a 100644
--- a/quic/server/state/ServerStateMachine.cpp
+++ b/quic/server/state/ServerStateMachine.cpp
@@ -1297,6 +1297,7 @@ void onServerReadDataFromOpen(
       handshakeConfirmed(conn);
     }
 
+    maybeScheduleAckForCongestionFeedback(readData.udpPacket, ackState);
     maybeHandleIncomingKeyUpdate(conn);
 
     // Update writable limit before processing the handshake data. This is so