diff --git a/gin/isolate_holder.cc b/gin/isolate_holder.cc
index e099fd3f03e5..4b362843e4f8 100644
--- a/gin/isolate_holder.cc
+++ b/gin/isolate_holder.cc
@@ -46,7 +46,8 @@ IsolateHolder::IsolateHolder(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner,
     AccessMode access_mode,
     AllowAtomicsWaitMode atomics_wait_mode,
-    IsolateCreationMode isolate_creation_mode)
+    IsolateCreationMode isolate_creation_mode,
+    v8::Isolate* isolate)
     : access_mode_(access_mode) {
   DCHECK(task_runner);
   DCHECK(task_runner->BelongsToCurrentThread());
@@ -54,7 +55,11 @@ IsolateHolder::IsolateHolder(
   v8::ArrayBuffer::Allocator* allocator = g_array_buffer_allocator;
   CHECK(allocator) << "You need to invoke gin::IsolateHolder::Initialize first";
 
-  isolate_ = v8::Isolate::Allocate();
+  if (!isolate) {
+    isolate_ = v8::Isolate::Allocate();
+  } else {
+    isolate_ = isolate;
+  }
   isolate_data_.reset(
       new PerIsolateData(isolate_, allocator, access_mode_, task_runner));
   if (isolate_creation_mode == IsolateCreationMode::kCreateSnapshot) {
diff --git a/gin/public/isolate_holder.h b/gin/public/isolate_holder.h
index 84cf66e6e9cd..cc0d65e4e4be 100644
--- a/gin/public/isolate_holder.h
+++ b/gin/public/isolate_holder.h
@@ -66,7 +66,8 @@ class GIN_EXPORT IsolateHolder {
       scoped_refptr<base::SingleThreadTaskRunner> task_runner,
       AccessMode access_mode,
       AllowAtomicsWaitMode atomics_wait_mode,
-      IsolateCreationMode isolate_creation_mode = IsolateCreationMode::kNormal);
+      IsolateCreationMode isolate_creation_mode = IsolateCreationMode::kNormal,
+      v8::Isolate* isolate = nullptr);
   ~IsolateHolder();
 
   // Should be invoked once before creating IsolateHolder instances to