diff --git a/dom/media/webaudio/AudioWorkletGlobalScope.cpp b/dom/media/webaudio/AudioWorkletGlobalScope.cpp
index 96e935f4bc19..ba4f423c200c 100644
--- a/dom/media/webaudio/AudioWorkletGlobalScope.cpp
+++ b/dom/media/webaudio/AudioWorkletGlobalScope.cpp
@@ -12,6 +12,7 @@
 #include "jsapi.h"
 #include "mozilla/dom/AudioWorkletGlobalScopeBinding.h"
 #include "mozilla/dom/AudioWorkletProcessor.h"
+#include "mozilla/dom/MessagePort.h"
 #include "mozilla/dom/StructuredCloneHolder.h"
 #include "mozilla/dom/WorkletPrincipals.h"
 #include "mozilla/dom/AudioParamDescriptorBinding.h"
@@ -296,6 +297,7 @@ AudioParamDescriptorMap AudioWorkletGlobalScope::DescriptorsFromJS(
 
 bool AudioWorkletGlobalScope::ConstructProcessor(
     const nsAString& aName, NotNull<StructuredCloneHolder*> aSerializedOptions,
+    UniqueMessagePortId& aPortIdentifier,
     JS::MutableHandle<JSObject*> aRetProcessor) {
   /**
    * See
@@ -307,10 +309,15 @@ bool AudioWorkletGlobalScope::ConstructProcessor(
   }
   JSContext* cx = jsapi.cx();
   ErrorResult rv;
-  /** TODO https://bugzilla.mozilla.org/show_bug.cgi?id=1565956
+  /**
    * 4. Let deserializedPort be the result of
    *    StructuredDeserialize(serializedPort, the current Realm).
    */
+  RefPtr<MessagePort> deserializedPort =
+      MessagePort::Create(this, aPortIdentifier, rv);
+  if (NS_WARN_IF(rv.MaybeSetPendingException(cx))) {
+    return false;
+  }
   /**
    * 5. Let deserializedOptions be the result of
    *    StructuredDeserialize(serializedOptions, the current Realm).
@@ -329,11 +336,14 @@ bool AudioWorkletGlobalScope::ConstructProcessor(
   // AudioWorkletNode has already checked the definition exists.
   // See also https://github.com/WebAudio/web-audio-api/issues/1854
   MOZ_ASSERT(processorCtor);
-  /** TODO https://bugzilla.mozilla.org/show_bug.cgi?id=1565956
+  /**
    * 7. Store nodeReference and deserializedPort to node reference and
    *    transferred port of this AudioWorkletGlobalScope's pending processor
    *    construction data respectively.
    */
+  // |nodeReference| is not required here because the "processorerror" event
+  // is thrown by WorkletNodeEngine::ConstructProcessor().
+  mPortForProcessor = std::move(deserializedPort);
   /**
    * 8. Construct a callback function from processorCtor with the argument
    *    of deserializedOptions.
@@ -344,6 +354,8 @@ bool AudioWorkletGlobalScope::ConstructProcessor(
   RefPtr<AudioWorkletProcessor> processor = processorCtor->Construct(
       options, rv, "AudioWorkletProcessor construction",
       CallbackFunction::eReportExceptions);
+  // https://github.com/WebAudio/web-audio-api/issues/2096
+  mPortForProcessor = nullptr;
   if (rv.Failed()) {
     rv.SuppressException();  // already reported
     return false;
diff --git a/dom/media/webaudio/AudioWorkletGlobalScope.h b/dom/media/webaudio/AudioWorkletGlobalScope.h
index 1975ce5f766b..03b1b97ffccb 100644
--- a/dom/media/webaudio/AudioWorkletGlobalScope.h
+++ b/dom/media/webaudio/AudioWorkletGlobalScope.h
@@ -19,7 +19,9 @@ class AudioWorkletImpl;
 namespace dom {
 
 class AudioWorkletProcessorConstructor;
+class MessagePort;
 class StructuredCloneHolder;
+class UniqueMessagePortId;
 
 class AudioWorkletGlobalScope final : public WorkletGlobalScope {
  public:
@@ -49,6 +51,7 @@ class AudioWorkletGlobalScope final : public WorkletGlobalScope {
   MOZ_CAN_RUN_SCRIPT
   bool ConstructProcessor(const nsAString& aName,
                           NotNull<StructuredCloneHolder*> aSerializedOptions,
+                          UniqueMessagePortId& aPortIdentifier,
                           JS::MutableHandle<JSObject*> aRetProcessor);
 
  private:
@@ -66,6 +69,10 @@ class AudioWorkletGlobalScope final : public WorkletGlobalScope {
   typedef nsRefPtrHashtable<nsStringHashKey, AudioWorkletProcessorConstructor>
       NodeNameToProcessorDefinitionMap;
   NodeNameToProcessorDefinitionMap mNameToProcessorMap;
+  // https://webaudio.github.io/web-audio-api/#pending-processor-construction-data-transferred-port
+  // This does not need to be traversed during cycle-collection because it is
+  // only set while this AudioWorkletGlobalScope is on the stack.
+  RefPtr<MessagePort> mPortForProcessor;
 };
 
 }  // namespace dom
diff --git a/dom/media/webaudio/AudioWorkletNode.cpp b/dom/media/webaudio/AudioWorkletNode.cpp
index 67ed27020096..2b69b3b05dc9 100644
--- a/dom/media/webaudio/AudioWorkletNode.cpp
+++ b/dom/media/webaudio/AudioWorkletNode.cpp
@@ -30,7 +30,8 @@ class WorkletNodeEngine final : public AudioNodeEngine {
   MOZ_CAN_RUN_SCRIPT
   void ConstructProcessor(AudioWorkletImpl* aWorkletImpl,
                           const nsAString& aName,
-                          NotNull<StructuredCloneHolder*> aSerializedOptions);
+                          NotNull<StructuredCloneHolder*> aSerializedOptions,
+                          UniqueMessagePortId& aPortIdentifier);
 
   void ProcessBlock(AudioNodeTrack* aTrack, GraphTime aFrom,
                     const AudioBlock& aInput, AudioBlock* aOutput,
@@ -120,13 +121,15 @@ void WorkletNodeEngine::SendProcessorError() {
 
 void WorkletNodeEngine::ConstructProcessor(
     AudioWorkletImpl* aWorkletImpl, const nsAString& aName,
-    NotNull<StructuredCloneHolder*> aSerializedOptions) {
+    NotNull<StructuredCloneHolder*> aSerializedOptions,
+    UniqueMessagePortId& aPortIdentifier) {
   MOZ_ASSERT(mInputs.mPorts.empty() && mOutputs.mPorts.empty());
   RefPtr<AudioWorkletGlobalScope> global = aWorkletImpl->GetGlobalScope();
   MOZ_ASSERT(global);  // global has already been used to register processor
   JS::RootingContext* cx = RootingCx();
   mProcessor.init(cx);
-  if (!global->ConstructProcessor(aName, aSerializedOptions, &mProcessor) ||
+  if (!global->ConstructProcessor(aName, aSerializedOptions, aPortIdentifier,
+                                  &mProcessor) ||
       // mInputs and mOutputs outer arrays are fixed length and so much of the
       // initialization need only be performed once (i.e. here).
       NS_WARN_IF(!mInputs.mPorts.growBy(InputCount())) ||
@@ -501,11 +504,12 @@ already_AddRefed<AudioWorkletNode> AudioWorkletNode::Constructor(
       // See bug 1535398.
       [track = audioWorkletNode->mTrack,
        workletImpl = RefPtr<AudioWorkletImpl>(workletImpl),
-       name = nsString(aName), options = std::move(serializedOptions)]()
-          MOZ_CAN_RUN_SCRIPT_BOUNDARY {
+       name = nsString(aName), options = std::move(serializedOptions),
+       portId = std::move(processorPortId)]()
+          MOZ_CAN_RUN_SCRIPT_BOUNDARY mutable {
             auto engine = static_cast<WorkletNodeEngine*>(track->Engine());
             engine->ConstructProcessor(workletImpl, name,
-                                       WrapNotNull(options.get()));
+                                       WrapNotNull(options.get()), portId);
           }));
 
   return audioWorkletNode.forget();