diff --git a/extension/module/bundled_module.cpp b/extension/module/bundled_module.cpp
index 083aef141a0..50dbfe69237 100644
--- a/extension/module/bundled_module.cpp
+++ b/extension/module/bundled_module.cpp
@@ -27,6 +27,8 @@ std::unique_ptr<BufferDataLoader> program_data_loader(
 }
 } // namespace
 
+namespace ET_BUNDLED_MODULE_NAMESPACE {
+
 BundledModule::BundledModule(
     const void* bundled_program_ptr,
     std::unique_ptr<runtime::MemoryAllocator> memory_allocator,
@@ -107,6 +109,6 @@ runtime::Error BundledModule::verify_method_outputs(
   return executorch::BUNDLED_PROGRAM_NAMESPACE::verify_method_outputs(
       *method, bundled_program_ptr_, testset_idx, rtol, atol);
 }
-
+} // namespace ET_BUNDLED_MODULE_NAMESPACE
 } // namespace extension
 } // namespace executorch
diff --git a/extension/module/bundled_module.h b/extension/module/bundled_module.h
index d254a2cdcb5..c75d83bcbad 100644
--- a/extension/module/bundled_module.h
+++ b/extension/module/bundled_module.h
@@ -10,9 +10,19 @@
 
 #include <executorch/extension/module/module.h>
 
+#ifdef USE_ATEN_LIB
+#define ET_BUNDLED_MODULE_NAMESPACE bundled_module::aten
+#else // !USE_ATEN_LIB
+#define ET_BUNDLED_MODULE_NAMESPACE bundled_module
+#endif // USE_ATEN_LIB
+
 namespace executorch {
 namespace extension {
 
+using ET_MODULE_NAMESPACE::Module;
+
+namespace ET_BUNDLED_MODULE_NAMESPACE {
+
 /**
  * A facade class for loading bundled programs and executing methods within
  * them.
@@ -119,5 +129,6 @@ class BundledModule : public Module {
   bool is_loaded_from_file_ = false;
 };
 
+} // namespace ET_BUNDLED_MODULE_NAMESPACE
 } // namespace extension
 } // namespace executorch
diff --git a/extension/module/module.cpp b/extension/module/module.cpp
index 721e9e5b89e..3212077d2ee 100644
--- a/extension/module/module.cpp
+++ b/extension/module/module.cpp
@@ -36,6 +36,7 @@
 
 namespace executorch {
 namespace extension {
+namespace ET_MODULE_NAMESPACE {
 
 using ET_RUNTIME_NAMESPACE::MethodMeta;
 using ET_RUNTIME_NAMESPACE::Program;
@@ -308,5 +309,6 @@ runtime::Error Module::set_output(
       output_tensor.mutable_data_ptr(), output_tensor.nbytes(), output_index);
 }
 
+} // namespace ET_MODULE_NAMESPACE
 } // namespace extension
 } // namespace executorch
diff --git a/extension/module/module.h b/extension/module/module.h
index e75d8383115..080ae53f43a 100644
--- a/extension/module/module.h
+++ b/extension/module/module.h
@@ -16,6 +16,12 @@
 
 #include <executorch/runtime/executor/program.h>
 
+#ifdef USE_ATEN_LIB
+#define ET_MODULE_NAMESPACE module::aten
+#else // !USE_ATEN_LIB
+#define ET_MODULE_NAMESPACE module
+#endif // USE_ATEN_LIB
+
 namespace executorch {
 namespace extension {
 
@@ -24,6 +30,9 @@ using ET_RUNTIME_NAMESPACE::MethodMeta;
 using ET_RUNTIME_NAMESPACE::NamedDataMap;
 using ET_RUNTIME_NAMESPACE::Program;
 
+class ExecuTorchJni;
+
+namespace ET_MODULE_NAMESPACE {
 /**
  * A facade class for loading programs and executing methods within them.
  */
@@ -493,9 +502,10 @@ class Module {
  protected:
   std::unordered_map<std::string, MethodHolder> methods_;
 
-  friend class ExecuTorchJni;
+  friend class executorch::extension::ExecuTorchJni;
 };
 
+} // namespace ET_MODULE_NAMESPACE
 } // namespace extension
 } // namespace executorch
 
@@ -503,6 +513,13 @@ namespace torch {
 namespace executor {
 // TODO(T197294990): Remove these deprecated aliases once all users have moved
 // to the new `::executorch` namespaces.
-using ::executorch::extension::Module;
+using ::executorch::extension::ET_MODULE_NAMESPACE::Module;
 } // namespace executor
 } // namespace torch
+
+namespace executorch {
+namespace extension {
+// backward compatible namespace alias
+using ::executorch::extension::ET_MODULE_NAMESPACE::Module;
+} // namespace extension
+} // namespace executorch
diff --git a/extension/module/test/bundled_module_test.cpp b/extension/module/test/bundled_module_test.cpp
index a07c5dd5486..0009c15d69e 100644
--- a/extension/module/test/bundled_module_test.cpp
+++ b/extension/module/test/bundled_module_test.cpp
@@ -9,7 +9,7 @@
 #include <executorch/extension/module/bundled_module.h>
 #include <gtest/gtest.h>
 
-using namespace ::executorch::extension;
+using namespace ::executorch::extension::ET_BUNDLED_MODULE_NAMESPACE;
 using namespace ::executorch::runtime;
 
 class BundledModuleTest : public ::testing::Test {