diff --git a/devtools/bundled_program/bundled_program.cpp b/devtools/bundled_program/bundled_program.cpp
index d174cbdcdad..54f84f6fef1 100644
--- a/devtools/bundled_program/bundled_program.cpp
+++ b/devtools/bundled_program/bundled_program.cpp
@@ -23,13 +23,21 @@
 #include <executorch/runtime/executor/method.h>
 #include <executorch/runtime/platform/log.h>
 
-namespace torch {
-namespace executor {
+using exec_aten::ArrayRef;
+using exec_aten::Half;
+using exec_aten::ScalarType;
+using exec_aten::Tensor;
+using ::executorch::runtime::Error;
+using ::executorch::runtime::EValue;
+using ::executorch::runtime::Method;
+using ::executorch::runtime::Result;
+
+namespace executorch {
 namespace bundled_program {
 
 namespace {
 
-#define kMaxDim 16
+constexpr size_t kMaxDim = 16;
 
 #ifdef USE_ATEN_LIB
 
@@ -53,6 +61,7 @@ at::Tensor tensor_like(bundled_program_flatbuffer::Tensor* bundled_tensor) {
 }
 
 #else // !USE_ATEN_LIB
+using torch::executor::TensorImpl;
 // Create a tensorimpl with same content using bundled tensor
 TensorImpl impl_like(bundled_program_flatbuffer::Tensor* bundled_tensor) {
   ScalarType scalar_type =
@@ -234,9 +243,9 @@ get_method_test_suite(
 } // namespace
 
 // Load testset_idx-th bundled data into the Method
-ET_NODISCARD Error LoadBundledInput(
+ET_NODISCARD Error load_bundled_input(
     Method& method,
-    serialized_bundled_program* bundled_program_ptr,
+    SerializedBundledProgram* bundled_program_ptr,
     size_t testset_idx) {
   ET_CHECK_OR_RETURN_ERROR(
       bundled_program_flatbuffer::BundledProgramBufferHasIdentifier(
@@ -319,19 +328,19 @@ ET_NODISCARD Error LoadBundledInput(
     ET_CHECK_OR_RETURN_ERROR(
         status == Error::Ok,
         NotSupported,
-        "set_input failed during load bundled inputs with status %" PRIu32,
-        static_cast<error_code_t>(status));
+        "set_input failed during load bundled inputs with status 0%" PRIx32,
+        static_cast<uint32_t>(status));
   }
 
-  internal::event_tracer_set_bundled_input_index(
+  ::executorch::runtime::internal::event_tracer_set_bundled_input_index(
       method.get_event_tracer(), testset_idx);
 
   return Error::Ok;
 }
 
-ET_NODISCARD Error VerifyResultWithBundledExpectedOutput(
+ET_NODISCARD Error verify_method_outputs(
     Method& method,
-    serialized_bundled_program* bundled_program_ptr,
+    SerializedBundledProgram* bundled_program_ptr,
     size_t testset_idx,
     double rtol,
     double atol) {
@@ -390,12 +399,12 @@ ET_NODISCARD Error VerifyResultWithBundledExpectedOutput(
   return Error::Ok;
 }
 
-ET_NODISCARD Error GetProgramData(
+ET_NODISCARD Error get_program_data(
     void* file_data,
     size_t file_data_len,
     const void** out_program_data,
     size_t* out_program_data_len) {
-  if (IsBundledProgram(file_data)) {
+  if (is_bundled_program(file_data, file_data_len)) {
     auto program_bundled =
         bundled_program_flatbuffer::GetBundledProgram(file_data);
     *out_program_data = program_bundled->program()->data();
@@ -410,11 +419,13 @@ ET_NODISCARD Error GetProgramData(
   return Error::Ok;
 }
 
-bool IsBundledProgram(void* file_data) {
+bool is_bundled_program(void* file_data, ET_UNUSED size_t file_data_len) {
+  // Even though the flatbuffer API doesn't accept a length, it's important to
+  // require one so that we could change the internal representation, or use a
+  // future API that does require a length.
   return bundled_program_flatbuffer::BundledProgramBufferHasIdentifier(
       file_data);
 }
 
 } // namespace bundled_program
-} // namespace executor
-} // namespace torch
+} // namespace executorch
diff --git a/devtools/bundled_program/bundled_program.h b/devtools/bundled_program/bundled_program.h
index 8b42923866e..884ca6f21bc 100644
--- a/devtools/bundled_program/bundled_program.h
+++ b/devtools/bundled_program/bundled_program.h
@@ -11,14 +11,13 @@
 #include <executorch/runtime/core/memory_allocator.h>
 #include <executorch/runtime/executor/method.h>
 
-namespace torch {
-namespace executor {
+namespace executorch {
 namespace bundled_program {
 
 /**
  * An opaque pointer to a serialized bundled program.
  */
-using serialized_bundled_program = const void;
+using SerializedBundledProgram = const void;
 
 /**
  * Load testset_idx-th bundled input of method_idx-th Method test in
@@ -31,9 +30,9 @@ using serialized_bundled_program = const void;
  * @returns Return Error::Ok if load successfully, or the error happens during
  * execution.
  */
-ET_NODISCARD Error LoadBundledInput(
-    Method& method,
-    serialized_bundled_program* bundled_program_ptr,
+ET_NODISCARD ::executorch::runtime::Error load_bundled_input(
+    ::executorch::runtime::Method& method,
+    SerializedBundledProgram* bundled_program_ptr,
     size_t testset_idx);
 
 /**
@@ -49,9 +48,9 @@ ET_NODISCARD Error LoadBundledInput(
  * @returns Return Error::Ok if two outputs match, or the error happens during
  * execution.
  */
-ET_NODISCARD Error VerifyResultWithBundledExpectedOutput(
-    Method& method,
-    serialized_bundled_program* bundled_program_ptr,
+ET_NODISCARD ::executorch::runtime::Error verify_method_outputs(
+    ::executorch::runtime::Method& method,
+    SerializedBundledProgram* bundled_program_ptr,
     size_t testset_idx,
     double rtol = 1e-5,
     double atol = 1e-8);
@@ -73,7 +72,7 @@ ET_NODISCARD Error VerifyResultWithBundledExpectedOutput(
  * in it, and out_program_data/out_program_data_len point to the data. Other
  * values on failure.
  */
-ET_NODISCARD Error GetProgramData(
+ET_NODISCARD ::executorch::runtime::Error get_program_data(
     void* file_data,
     size_t file_data_len,
     const void** out_program_data,
@@ -83,11 +82,61 @@ ET_NODISCARD Error GetProgramData(
  * Checks whether the given file is a bundled program.
  *
  * @param[in] file_data The contents of the given file.
+ * @param[in] file_data_len The length of file_data, in bytes.
  *
  * @returns true if the given file is a bundled program, false otherwise
  */
-bool IsBundledProgram(void* file_data);
+bool is_bundled_program(void* file_data, size_t file_data_len);
+
+/// DEPRECATED: Use the version with the file_data_len parameter.
+ET_DEPRECATED inline bool is_bundled_program(void* file_data) {
+  // 128 is enough data to contain the identifier in the flatbuffer header.
+  return is_bundled_program(file_data, 128);
+}
+
+} // namespace bundled_program
+} // namespace executorch
+
+namespace torch {
+namespace executor {
+namespace bundled_program {
+// TODO(T197294990): Remove these deprecated aliases once all users have moved
+// to the new `::executorch` namespaces.
+using serialized_bundled_program =
+    ::executorch::bundled_program::SerializedBundledProgram;
+
+ET_NODISCARD inline ::executorch::runtime::Error LoadBundledInput(
+    ::executorch::runtime::Method& method,
+    serialized_bundled_program* bundled_program_ptr,
+    size_t testset_idx) {
+  return ::executorch::bundled_program::load_bundled_input(
+      method, bundled_program_ptr, testset_idx);
+}
+
+ET_NODISCARD inline ::executorch::runtime::Error
+VerifyResultWithBundledExpectedOutput(
+    ::executorch::runtime::Method& method,
+    serialized_bundled_program* bundled_program_ptr,
+    size_t testset_idx,
+    double rtol = 1e-5,
+    double atol = 1e-8) {
+  return ::executorch::bundled_program::verify_method_outputs(
+      method, bundled_program_ptr, testset_idx, rtol, atol);
+}
+
+ET_NODISCARD inline ::executorch::runtime::Error GetProgramData(
+    void* file_data,
+    size_t file_data_len,
+    const void** out_program_data,
+    size_t* out_program_data_len) {
+  return ::executorch::bundled_program::get_program_data(
+      file_data, file_data_len, out_program_data, out_program_data_len);
+}
 
+inline bool IsBundledProgram(void* file_data) {
+  // 128 is enough data to contain the identifier in the flatbuffer header.
+  return ::executorch::bundled_program::is_bundled_program(file_data, 128);
+}
 } // namespace bundled_program
 } // namespace executor
 } // namespace torch
diff --git a/extension/pybindings/pybindings.cpp b/extension/pybindings/pybindings.cpp
index 000cecf4b23..57bc44d1394 100644
--- a/extension/pybindings/pybindings.cpp
+++ b/extension/pybindings/pybindings.cpp
@@ -71,6 +71,7 @@ void et_pal_emit_log_message(
 }
 
 namespace py = pybind11;
+using executorch::bundled_program::verify_method_outputs;
 using ::executorch::extension::BufferDataLoader;
 using ::executorch::extension::MallocMemoryAllocator;
 using ::executorch::extension::MmapDataLoader;
@@ -92,8 +93,6 @@ using ::executorch::runtime::Span;
 using ::executorch::runtime::Tag;
 using torch::executor::etdump_result;
 using torch::executor::ETDumpGen;
-using torch::executor::bundled_program::LoadBundledInput;
-using torch::executor::bundled_program::VerifyResultWithBundledExpectedOutput;
 
 #ifndef USE_ATEN_LIB
 using ::executorch::extension::alias_attensor_to_etensor;
@@ -655,11 +654,11 @@ struct PyModule final {
       const std::string method_name,
       size_t testset_idx) {
     const void* bundled_program_ptr = m.get_bundled_program_ptr();
-    Error status = LoadBundledInput(
+    Error status = executorch::bundled_program::load_bundled_input(
         module_->get_method(method_name), bundled_program_ptr, testset_idx);
     THROW_IF_ERROR(
         status,
-        "LoadBundledInput failed with status %" PRIu32,
+        "load_bundled_input failed with status 0x%" PRIx32,
         static_cast<uint32_t>(status));
   }
 
@@ -671,13 +670,14 @@ struct PyModule final {
       double atol = 1e-8) {
     const void* bundled_program_ptr = m.get_bundled_program_ptr();
     auto& method = module_->get_method(method_name);
-    Error status = LoadBundledInput(method, bundled_program_ptr, testset_idx);
+    Error status = executorch::bundled_program::load_bundled_input(
+        method, bundled_program_ptr, testset_idx);
     THROW_IF_ERROR(
         status,
-        "LoadBundledInput failed with status %" PRIu32,
+        "load_bundled_input failed with status 0x%" PRIx32,
         static_cast<uint32_t>(status));
     py::list outputs = plan_execute(method_name);
-    status = VerifyResultWithBundledExpectedOutput(
+    status = executorch::bundled_program::verify_method_outputs(
         method, bundled_program_ptr, testset_idx, rtol, atol);
     THROW_IF_ERROR(
         status,