diff --git a/js/src/builtin/streams/WritableStreamDefaultWriter.cpp b/js/src/builtin/streams/WritableStreamDefaultWriter.cpp
index 17216b9c2593..cea6b3215066 100644
--- a/js/src/builtin/streams/WritableStreamDefaultWriter.cpp
+++ b/js/src/builtin/streams/WritableStreamDefaultWriter.cpp
@@ -18,7 +18,7 @@
 #include "builtin/streams/MiscellaneousOperations.h"  // js::ReturnPromiseRejectedWithPendingError
 #include "builtin/streams/WritableStream.h"           // js::WritableStream
 #include "builtin/streams/WritableStreamOperations.h"  // js::WritableStreamCloseQueuedOrInFlight
-#include "builtin/streams/WritableStreamWriterOperations.h"  // js::WritableStreamDefaultWriter{GetDesiredSize,Release,Write}
+#include "builtin/streams/WritableStreamWriterOperations.h"  // js::WritableStreamDefaultWriter{Abort,GetDesiredSize,Release,Write}
 #include "js/CallArgs.h"                              // JS::CallArgs{,FromVp}
 #include "js/Class.h"                        // js::ClassSpec, JS_NULL_CLASS_OPS
 #include "js/PropertySpec.h"  // JS{Function,Property}Spec, JS_{FS,PS}_END, JS_{FN,PSG}
@@ -154,6 +154,42 @@ static MOZ_MUST_USE bool WritableStream_ready(JSContext* cx, unsigned argc,
   return true;
 }
 
+/**
+ * Streams spec, 4.5.4.4. abort(reason)
+ */
+static MOZ_MUST_USE bool WritableStream_abort(JSContext* cx, unsigned argc,
+                                              Value* vp) {
+  CallArgs args = CallArgsFromVp(argc, vp);
+
+  // Step 1: If ! IsWritableStreamDefaultWriter(this) is false, return a promise
+  //         rejected with a TypeError exception.
+  Rooted<WritableStreamDefaultWriter*> unwrappedWriter(
+      cx,
+      UnwrapAndTypeCheckThis<WritableStreamDefaultWriter>(cx, args, "abort"));
+  if (!unwrappedWriter) {
+    return ReturnPromiseRejectedWithPendingError(cx, args);
+  }
+
+  // Step 2: If this.[[ownerWritableStream]] is undefined, return a promise
+  //         rejected with a TypeError exception.
+  if (!unwrappedWriter->hasStream()) {
+    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
+                              JSMSG_WRITABLESTREAMWRITER_NOT_OWNED, "abort");
+    return ReturnPromiseRejectedWithPendingError(cx, args);
+  }
+
+  // Step 3: Return ! WritableStreamDefaultWriterAbort(this, reason).
+  JSObject* promise =
+      WritableStreamDefaultWriterAbort(cx, unwrappedWriter, args.get(0));
+  if (!promise) {
+    return false;
+  }
+  cx->check(promise);
+
+  args.rval().setObject(*promise);
+  return true;
+}
+
 /**
  * Streams spec, 4.5.4.5. close()
  */
@@ -289,6 +325,7 @@ static const JSPropertySpec WritableStreamDefaultWriter_properties[] = {
     JS_PSG("ready", WritableStream_ready, 0), JS_PS_END};
 
 static const JSFunctionSpec WritableStreamDefaultWriter_methods[] = {
+    JS_FN("abort", WritableStream_abort, 1, 0),
     JS_FN("close", WritableStream_close, 0, 0),
     JS_FN("releaseLock", WritableStream_releaseLock, 0, 0),
     JS_FN("write", WritableStream_write, 1, 0), JS_FS_END};
diff --git a/js/src/builtin/streams/WritableStreamWriterOperations.cpp b/js/src/builtin/streams/WritableStreamWriterOperations.cpp
index 30fbf3107dbb..ae4f287c8713 100644
--- a/js/src/builtin/streams/WritableStreamWriterOperations.cpp
+++ b/js/src/builtin/streams/WritableStreamWriterOperations.cpp
@@ -20,7 +20,7 @@
 #include "builtin/streams/WritableStreamDefaultController.h"  // js::WritableStream::controller
 #include "builtin/streams/WritableStreamDefaultControllerOperations.h"  // js::WritableStreamDefaultController{Close,GetDesiredSize}
 #include "builtin/streams/WritableStreamDefaultWriter.h"  // js::WritableStreamDefaultWriter
-#include "builtin/streams/WritableStreamOperations.h"  // js::WritableStreamCloseQueuedOrInFlight
+#include "builtin/streams/WritableStreamOperations.h"  // js::WritableStream{Abort,CloseQueuedOrInFlight}
 #include "js/Value.h"  // JS::Value, JS::{Int32,Null}Value
 #include "vm/Compartment.h"  // JS::Compartment
 #include "vm/JSContext.h"    // JSContext
@@ -44,6 +44,28 @@ using js::PromiseObject;
 
 /*** 4.6. Writable stream writer abstract operations ************************/
 
+/**
+ * Streams spec, 4.6.2.
+ * WritableStreamDefaultWriterAbort ( writer, reason )
+ */
+JSObject* js::WritableStreamDefaultWriterAbort(
+    JSContext* cx, Handle<WritableStreamDefaultWriter*> unwrappedWriter,
+    Handle<Value> reason) {
+  cx->check(reason);
+
+  // Step 1: Let stream be writer.[[ownerWritableStream]].
+  // Step 2: Assert: stream is not undefined.
+  MOZ_ASSERT(unwrappedWriter->hasStream());
+  Rooted<WritableStream*> unwrappedStream(
+      cx, UnwrapStreamFromWriter(cx, unwrappedWriter));
+  if (!unwrappedStream) {
+    return nullptr;
+  }
+
+  // Step 3: Return ! WritableStreamAbort(stream, reason).
+  return WritableStreamAbort(cx, unwrappedStream, reason);
+}
+
 /**
  * Streams spec, 4.6.3.
  * WritableStreamDefaultWriterClose ( writer )
diff --git a/js/src/builtin/streams/WritableStreamWriterOperations.h b/js/src/builtin/streams/WritableStreamWriterOperations.h
index febbca13bc87..6446d4fc32f0 100644
--- a/js/src/builtin/streams/WritableStreamWriterOperations.h
+++ b/js/src/builtin/streams/WritableStreamWriterOperations.h
@@ -21,6 +21,10 @@ namespace js {
 
 class WritableStreamDefaultWriter;
 
+extern JSObject* WritableStreamDefaultWriterAbort(
+    JSContext* cx, JS::Handle<WritableStreamDefaultWriter*> unwrappedWriter,
+    JS::Handle<JS::Value> reason);
+
 extern JSObject* WritableStreamDefaultWriterClose(
     JSContext* cx, JS::Handle<WritableStreamDefaultWriter*> unwrappedWriter);