diff --git a/components/atoms/static_atoms.txt b/components/atoms/static_atoms.txt
index ebf3b512d6a..7a6022cb64c 100644
--- a/components/atoms/static_atoms.txt
+++ b/components/atoms/static_atoms.txt
@@ -97,6 +97,7 @@ seeked
 seeking
 select
 serif
+signalingstatechange
 srclang
 statechange
 storage
diff --git a/components/script/dom/rtcpeerconnection.rs b/components/script/dom/rtcpeerconnection.rs
index 8e12e2ab012..f9bb844d8fe 100644
--- a/components/script/dom/rtcpeerconnection.rs
+++ b/components/script/dom/rtcpeerconnection.rs
@@ -8,7 +8,7 @@ use crate::dom::bindings::codegen::Bindings::RTCPeerConnectionBinding;
 use crate::dom::bindings::codegen::Bindings::RTCPeerConnectionBinding::RTCPeerConnectionMethods;
 use crate::dom::bindings::codegen::Bindings::RTCPeerConnectionBinding::{
     RTCAnswerOptions, RTCBundlePolicy, RTCConfiguration, RTCIceConnectionState,
-    RTCIceGatheringState, RTCOfferOptions,
+    RTCIceGatheringState, RTCOfferOptions, RTCSignalingState,
 };
 use crate::dom::bindings::codegen::Bindings::RTCSessionDescriptionBinding::{
     RTCSdpType, RTCSessionDescriptionInit,
@@ -38,7 +38,7 @@ use dom_struct::dom_struct;
 use servo_media::streams::MediaStream as BackendMediaStream;
 use servo_media::webrtc::{
     BundlePolicy, GatheringState, IceCandidate, IceConnectionState, SdpType, SessionDescription,
-    WebRtcController, WebRtcSignaller,
+    SignalingState, WebRtcController, WebRtcSignaller,
 };
 use servo_media::ServoMedia;
 use servo_media_auto::Backend;
@@ -63,6 +63,7 @@ pub struct RTCPeerConnection {
     remote_description: MutNullableDom<RTCSessionDescription>,
     gathering_state: Cell<RTCIceGatheringState>,
     ice_connection_state: Cell<RTCIceConnectionState>,
+    signaling_state: Cell<RTCSignalingState>,
 }
 
 struct RTCSignaller {
@@ -116,6 +117,17 @@ impl WebRtcSignaller for RTCSignaller {
         );
     }
 
+    fn update_signaling_state(&self, state: SignalingState) {
+        let this = self.trusted.clone();
+        let _ = self.task_source.queue_with_canceller(
+            task!(update_signaling_state: move || {
+                let this = this.root();
+                this.update_signaling_state(state);
+            }),
+            &self.canceller,
+        );
+    }
+
     fn on_add_stream(&self, _: Box<BackendMediaStream>) {}
 
     fn close(&self) {
@@ -136,6 +148,7 @@ impl RTCPeerConnection {
             remote_description: Default::default(),
             gathering_state: Cell::new(RTCIceGatheringState::New),
             ice_connection_state: Cell::new(RTCIceConnectionState::New),
+            signaling_state: Cell::new(RTCSignalingState::Stable),
         }
     }
 
@@ -294,6 +307,28 @@ impl RTCPeerConnection {
         event.upcast::<Event>().fire(self.upcast());
     }
 
+    fn update_signaling_state(&self, state: SignalingState) {
+        if self.closed.get() {
+            return;
+        }
+
+        let state: RTCSignalingState = state.into();
+
+        if state == self.signaling_state.get() {
+            return;
+        }
+
+        self.signaling_state.set(state);
+
+        let event = Event::new(
+            &self.global(),
+            atom!("signalingstatechange"),
+            EventBubbles::DoesNotBubble,
+            EventCancelable::NotCancelable,
+        );
+        event.upcast::<Event>().fire(self.upcast());
+    }
+
     fn create_offer(&self) {
         let generation = self.offer_answer_generation.get();
         let (task_source, canceller) = self
@@ -386,6 +421,13 @@ impl RTCPeerConnectionMethods for RTCPeerConnection {
         SetOnnegotiationneeded
     );
 
+    /// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-signalingstatechange
+    event_handler!(
+        signalingstatechange,
+        GetOnsignalingstatechange,
+        SetOnsignalingstatechange
+    );
+
     /// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-addicecandidate
     fn AddIceCandidate(&self, candidate: &RTCIceCandidateInit) -> Rc<Promise> {
         let p = Promise::new(&self.global());
@@ -539,6 +581,11 @@ impl RTCPeerConnectionMethods for RTCPeerConnection {
     fn IceConnectionState(&self) -> RTCIceConnectionState {
         self.ice_connection_state.get()
     }
+
+    /// https://www.w3.org/TR/webrtc/#dom-rtcpeerconnection-signalingstate
+    fn SignalingState(&self) -> RTCSignalingState {
+        self.signaling_state.get()
+    }
 }
 
 impl From<SessionDescription> for RTCSessionDescriptionInit {
@@ -594,3 +641,16 @@ impl From<IceConnectionState> for RTCIceConnectionState {
         }
     }
 }
+
+impl From<SignalingState> for RTCSignalingState {
+    fn from(state: SignalingState) -> Self {
+        match state {
+            SignalingState::Stable => RTCSignalingState::Stable,
+            SignalingState::HaveLocalOffer => RTCSignalingState::Have_local_offer,
+            SignalingState::HaveRemoteOffer => RTCSignalingState::Have_remote_offer,
+            SignalingState::HaveLocalPranswer => RTCSignalingState::Have_local_pranswer,
+            SignalingState::HaveRemotePranswer => RTCSignalingState::Have_remote_pranswer,
+            SignalingState::Closed => RTCSignalingState::Closed,
+        }
+    }
+}
diff --git a/components/script/dom/webidls/RTCPeerConnection.webidl b/components/script/dom/webidls/RTCPeerConnection.webidl
index ec74e551bc5..60447917b3e 100644
--- a/components/script/dom/webidls/RTCPeerConnection.webidl
+++ b/components/script/dom/webidls/RTCPeerConnection.webidl
@@ -18,7 +18,7 @@ interface RTCPeerConnection : EventTarget {
     // readonly attribute RTCSessionDescription? currentRemoteDescription;
     // readonly attribute RTCSessionDescription? pendingRemoteDescription;
     Promise<void>                      addIceCandidate(optional RTCIceCandidateInit candidate);
-    // readonly attribute RTCSignalingState      signalingState;
+    readonly attribute RTCSignalingState      signalingState;
     readonly attribute RTCIceGatheringState   iceGatheringState;
     readonly attribute RTCIceConnectionState  iceConnectionState;
     // readonly attribute RTCPeerConnectionState connectionState;
@@ -30,7 +30,7 @@ interface RTCPeerConnection : EventTarget {
              attribute EventHandler           onnegotiationneeded;
              attribute EventHandler           onicecandidate;
     //          attribute EventHandler           onicecandidateerror;
-    //          attribute EventHandler           onsignalingstatechange;
+             attribute EventHandler           onsignalingstatechange;
              attribute EventHandler           oniceconnectionstatechange;
              attribute EventHandler           onicegatheringstatechange;
     //          attribute EventHandler           onconnectionstatechange;
@@ -105,3 +105,12 @@ enum RTCIceConnectionState {
     "failed",
     "closed"
 };
+
+enum RTCSignalingState {
+    "stable",
+    "have-local-offer",
+    "have-remote-offer",
+    "have-local-pranswer",
+    "have-remote-pranswer",
+    "closed"
+};