diff --git a/include/onnxruntime/core/graph/graph.h b/include/onnxruntime/core/graph/graph.h
index 360ea68380..46a485c1fc 100644
--- a/include/onnxruntime/core/graph/graph.h
+++ b/include/onnxruntime/core/graph/graph.h
@@ -32,6 +32,7 @@
 
 #include "core/common/common.h"
 #include "core/common/const_pointer_container.h"
+#include "core/common/inlined_containers_fwd.h"
 #include "core/common/path.h"
 #include "core/common/status.h"
 #include "core/common/logging/logging.h"
@@ -675,7 +676,15 @@ class Graph {
   Note: This currently has linear time complexity. There is room for improvement but it would likely require changes to
   how initializer tensors are stored and tracked.
   */
-  common::Status ReplaceInitializedTensor(const ONNX_NAMESPACE::TensorProto& new_initializer);
+  common::Status ReplaceInitializedTensor(ONNX_NAMESPACE::TensorProto new_initializer);
+
+#if !defined(DISABLE_EXTERNAL_INITIALIZERS)
+  /** This function takes externally provided data for initializers with external data
+  *    and replaces graph initializers with its content.
+  */
+  common::Status InjectExternalInitializedTensors(const InlinedHashMap<std::string, OrtValue>& external_initializers);
+#endif  // !defined(DISABLE_EXTERNAL_INITIALIZERS)
+
 #endif  // !defined(ORT_MINIMAL_BUILD)
 
 #if !defined(ORT_MINIMAL_BUILD) || defined(ORT_EXTENDED_MINIMAL_BUILD)
@@ -1465,6 +1474,9 @@ class Graph {
   // so they can be used to resolve outer scope dependencies when running BuildConnections for the subgraphs.
   common::Status SetOuterScopeNodeArgs(const std::unordered_set<std::string>& outer_scope_node_args);
 
+  // Implementation for initializer replacement
+  Status ReplaceInitializedTensorImpl(ONNX_NAMESPACE::TensorProto new_initializer, bool is_external);
+
   // Clear all unused initializers and NodeArgs
   void CleanUnusedInitializersAndNodeArgs(const std::unordered_set<std::string>* initializer_names_to_preserve = nullptr);
 
diff --git a/include/onnxruntime/core/session/onnxruntime_c_api.h b/include/onnxruntime/core/session/onnxruntime_c_api.h
index fc8ca5276c..922adca4ab 100644
--- a/include/onnxruntime/core/session/onnxruntime_c_api.h
+++ b/include/onnxruntime/core/session/onnxruntime_c_api.h
@@ -30,7 +30,7 @@
 *
 * This value is used by some API functions to behave as this version of the header expects.
 */
-#define ORT_API_VERSION 12 
+#define ORT_API_VERSION 12
 
 #ifdef __cplusplus
 extern "C" {
@@ -483,7 +483,7 @@ typedef struct OrtTensorRTProviderOptions {
   const char* trt_engine_decryption_lib_path;   // specify engine decryption library path
   int trt_force_sequential_engine_build;        // force building TensorRT engine sequentially. Default 0 = false, nonzero = true
   // This is the legacy struct and don't add new fields here.
-  // For new field that can be represented by string, please add it in include/onnxruntime/core/providers/tensorrt/tensorrt_provider_options.h   
+  // For new field that can be represented by string, please add it in include/onnxruntime/core/providers/tensorrt/tensorrt_provider_options.h
   // For non-string field, need to create a new separate api to handle it.
 } OrtTensorRTProviderOptions;
 
@@ -492,9 +492,9 @@ typedef struct OrtTensorRTProviderOptions {
 * \see OrtApi::SessionOptionsAppendExecutionProvider_MIGraphX
 */
 typedef struct OrtMIGraphXProviderOptions {
-  int device_id;                                // hip device id.
-  int migraphx_fp16_enable;                     // enable MIGraphX FP16 precision. Default 0 = false, nonzero = true
-  int migraphx_int8_enable;                     // enable MIGraphX INT8 precision. Default 0 = false, nonzero = true
+  int device_id;             // hip device id.
+  int migraphx_fp16_enable;  // enable MIGraphX FP16 precision. Default 0 = false, nonzero = true
+  int migraphx_int8_enable;  // enable MIGraphX INT8 precision. Default 0 = false, nonzero = true
 } OrtMIGraphXProviderOptions;
 
 /** \brief OpenVINO Provider Options
@@ -3304,6 +3304,31 @@ struct OrtApi {
   */
   ORT_API2_STATUS(SessionOptionsAppendExecutionProvider_MIGraphX,
                   _In_ OrtSessionOptions* options, _In_ const OrtMIGraphXProviderOptions* migraphx_options);
+
+ /** \brief Replace initialized Tensors with external data with the data provided in initializers.
+  *
+  * The function will find the initialized TensorProtos with external data in the graph with the provided names and
+  * replace them with the provided tensors. The API verifies that the TensorProto being replaced
+  * has an external data reference and has the same name, dimensions and data type as its replacement. The replacement
+  * will occur before any of the optimizations take place. The data will be copied into the graph
+  * since TensorProto can't refer to the user provided buffers.
+  *
+  * Once the model has been loaded, the OrtValue(s) added to SessionOptions instance will be removed
+  * from the internal SessionOptions copy to save memory, the user provided buffers can then be deallocated
+  * and the SessionOptions instance that refers to them can be destroyed.
+  *
+  * \param[in] options
+  * \param[in] initializer_names Array of null terminated UTF-8 encoded strings of the initializers names.
+  * \param[in] initializers Array of ::OrtValue type
+  * \param[in] initializers_num Number of elements in the initializer_names and initializers
+  *
+  * \snippet{doc} snippets.dox OrtStatus Return Value
+  *
+  * \since Version 1.12.
+  */
+  ORT_API2_STATUS(AddExternalInitializers, _In_ OrtSessionOptions* options,
+                  _In_reads_(input_len) const char* const* initializer_names,
+                  _In_reads_(input_len) const OrtValue* const* initializers, size_t initializers_num);
 };
 
 /*
@@ -3373,8 +3398,6 @@ ORT_API_STATUS(OrtSessionOptionsAppendExecutionProvider_CUDA, _In_ OrtSessionOpt
  * \param device_id HIP device id, starts from zero.
 */
 ORT_API_STATUS(OrtSessionOptionsAppendExecutionProvider_MIGraphX, _In_ OrtSessionOptions* options, int device_id);
-
-
 #ifdef __cplusplus
 }
 #endif
diff --git a/include/onnxruntime/core/session/onnxruntime_cxx_api.h b/include/onnxruntime/core/session/onnxruntime_cxx_api.h
index 5c29a0f82a..6f19d2dcb3 100644
--- a/include/onnxruntime/core/session/onnxruntime_cxx_api.h
+++ b/include/onnxruntime/core/session/onnxruntime_cxx_api.h
@@ -359,6 +359,7 @@ struct SessionOptions : Base<OrtSessionOptions> {
 
   SessionOptions& AddConfigEntry(const char* config_key, const char* config_value);  ///< Wraps OrtApi::AddSessionConfigEntry
   SessionOptions& AddInitializer(const char* name, const OrtValue* ort_val);         ///< Wraps OrtApi::AddInitializer
+  SessionOptions& AddExternalInitializers(const std::vector<std::string>& names, const std::vector<Value>& ort_values);  ///< Wraps OrtApi::AddExternalInitializers
 
   SessionOptions& AppendExecutionProvider_CUDA(const OrtCUDAProviderOptions& provider_options);          ///< Wraps OrtApi::SessionOptionsAppendExecutionProvider_CUDA
   SessionOptions& AppendExecutionProvider_ROCM(const OrtROCMProviderOptions& provider_options);          ///< Wraps OrtApi::SessionOptionsAppendExecutionProvider_ROCM
diff --git a/include/onnxruntime/core/session/onnxruntime_cxx_inline.h b/include/onnxruntime/core/session/onnxruntime_cxx_inline.h
index 063acb1702..57381301fc 100644
--- a/include/onnxruntime/core/session/onnxruntime_cxx_inline.h
+++ b/include/onnxruntime/core/session/onnxruntime_cxx_inline.h
@@ -503,6 +503,24 @@ inline SessionOptions& SessionOptions::AddInitializer(const char* name, const Or
   return *this;
 }
 
+inline SessionOptions& SessionOptions::AddExternalInitializers(const std::vector<std::string>& names,
+                                                               const std::vector<Value>& ort_values) {
+  const size_t inputs_num = names.size();
+  if (inputs_num != ort_values.size()) {
+    ORT_CXX_API_THROW("Expecting names and ort_values to have the same length", ORT_INVALID_ARGUMENT);
+  }
+  std::vector<const char*> names_ptr;
+  std::vector<const OrtValue*> ort_values_ptrs;
+  names_ptr.reserve(inputs_num);
+  ort_values_ptrs.reserve(inputs_num);
+  for (size_t i = 0; i < inputs_num; ++i) {
+    names_ptr.push_back(names[i].c_str());
+    ort_values_ptrs.push_back(ort_values[i]);
+  }
+  ThrowOnError(GetApi().AddExternalInitializers(p_, names_ptr.data(), ort_values_ptrs.data(), inputs_num));
+  return *this;
+}
+
 inline SessionOptions& SessionOptions::AppendExecutionProvider_CUDA(const OrtCUDAProviderOptions& provider_options) {
   ThrowOnError(GetApi().SessionOptionsAppendExecutionProvider_CUDA(p_, &provider_options));
   return *this;
@@ -1133,7 +1151,7 @@ inline T* CustomOpApi::GetTensorMutableData(_Inout_ OrtValue* value) {
 
 inline const OrtMemoryInfo* CustomOpApi::GetTensorMemoryInfo(_In_ const OrtValue* value) {
   const OrtMemoryInfo* mem_info;
-  ThrowOnError(api_.GetTensorMemoryInfo(value, &mem_info)); 
+  ThrowOnError(api_.GetTensorMemoryInfo(value, &mem_info));
   return mem_info;
 }
 
diff --git a/onnxruntime/core/framework/session_options.cc b/onnxruntime/core/framework/session_options.cc
index 2e41b05440..cb625e7f55 100644
--- a/onnxruntime/core/framework/session_options.cc
+++ b/onnxruntime/core/framework/session_options.cc
@@ -7,30 +7,54 @@
 
 namespace onnxruntime {
 
-Status SessionOptions::AddInitializer(_In_z_ const char* name, _In_ const OrtValue* val) noexcept {
-  // input validation
+namespace {
+
+Status CheckInitializer(const char* name, const OrtValue* val) {
   if (name == nullptr) {
-    return ORT_MAKE_STATUS(ONNXRUNTIME, INVALID_ARGUMENT, "Received nullptr for name.");
+    return ORT_MAKE_STATUS(ONNXRUNTIME, INVALID_ARGUMENT, "Received nullptr for name");
   }
 
   if (val == nullptr) {
-    return ORT_MAKE_STATUS(ONNXRUNTIME, INVALID_ARGUMENT, "Received nullptr for OrtValue.");
+    return ORT_MAKE_STATUS(ONNXRUNTIME, INVALID_ARGUMENT, "Received nullptr for OrtValue");
   }
 
   if (!val->IsTensor()) {
     return ORT_MAKE_STATUS(ONNXRUNTIME, INVALID_ARGUMENT, "Received OrtValue is not a tensor. Only tensors are supported.");
   }
-
   if (val->Get<Tensor>().OwnsBuffer()) {
     return ORT_MAKE_STATUS(ONNXRUNTIME, INVALID_ARGUMENT, "Buffer containing the initializer must be owned by the user.");
   }
+  return Status::OK();
+}
 
+}  // namespace
+
+Status SessionOptions::AddInitializer(_In_z_ const char* name, _In_ const OrtValue* val) {
+  // input validation
+  ORT_RETURN_IF_ERROR(CheckInitializer(name, val));
   // now do the actual work
-  auto rc = initializers_to_share_map.insert({name, val});
-  if (!rc.second) {
-    return ORT_MAKE_STATUS(ONNXRUNTIME, INVALID_ARGUMENT, "An OrtValue for this name has already been added.");
+  bool result = initializers_to_share_map.emplace(name, val).second;
+
+  if (!result) {
+    return ORT_MAKE_STATUS(ONNXRUNTIME, INVALID_ARGUMENT, "An OrtValue for this name has already been added: ", name);
   }
 
   return Status::OK();
 }
+
+#if !defined(ORT_MINIMAL_BUILD) && !defined(DISABLE_EXTERNAL_INITIALIZERS)
+Status SessionOptions::AddExternalInitializers(gsl::span<const std::string> names, gsl::span<const OrtValue> values) {
+  const auto init_num = names.size();
+  ORT_ENFORCE(init_num == values.size(), "Expecting same size spans");
+  external_initializers.reserve(external_initializers.size() + init_num);
+  for (size_t i = 0; i < init_num; ++i) {
+    ORT_RETURN_IF_ERROR(CheckInitializer(names[i].c_str(), &values[i]));
+    bool result = external_initializers.emplace(names[i], values[i]).second;
+    if (!result) {
+      return ORT_MAKE_STATUS(ONNXRUNTIME, INVALID_ARGUMENT, "An OrtValue for this name has already been added: ", names[i]);
+    }
+  }
+  return Status::OK();
+}
+#endif  // !defined(ORT_MINIMAL_BUILD) && !defined(DISABLE_EXTERNAL_INITIALIZERS)
 }  // namespace onnxruntime
diff --git a/onnxruntime/core/framework/session_options.h b/onnxruntime/core/framework/session_options.h
index 09e679a657..c3012299a3 100644
--- a/onnxruntime/core/framework/session_options.h
+++ b/onnxruntime/core/framework/session_options.h
@@ -6,6 +6,7 @@
 #include <string>
 #include <vector>
 #include "core/common/gsl_suppress.h"
+#include "core/common/inlined_containers.h"
 #include "core/session/onnxruntime_c_api.h"
 #include "core/optimizer/graph_transformer_level.h"
 #include "core/util/thread_utils.h"
@@ -119,7 +120,13 @@ struct SessionOptions {
   std::unordered_map<std::string, const OrtValue*> initializers_to_share_map;
 
   // See onnxruntime_c_api.h for detailed documentation.
-  Status AddInitializer(_In_z_ const char* name, _In_ const OrtValue* val) noexcept;
+  Status AddInitializer(_In_z_ const char* name, _In_ const OrtValue* val);
+
+#if !defined(ORT_MINIMAL_BUILD)  && !defined(DISABLE_EXTERNAL_INITIALIZERS)
+  // Customer supplied pre-processed data for external initializers
+  InlinedHashMap<std::string, OrtValue> external_initializers;
+  Status AddExternalInitializers(gsl::span<const std::string> names, gsl::span<const OrtValue> values);
+#endif
 
   // custom function callback to create a thread
   OrtCustomCreateThreadFn custom_create_thread_fn = nullptr;
diff --git a/onnxruntime/core/framework/tensorprotoutils.cc b/onnxruntime/core/framework/tensorprotoutils.cc
index 5b5b542643..986cd6b05c 100644
--- a/onnxruntime/core/framework/tensorprotoutils.cc
+++ b/onnxruntime/core/framework/tensorprotoutils.cc
@@ -125,8 +125,8 @@ static Status GetExternalDataInfo(const ONNX_NAMESPACE::TensorProto& tensor_prot
   ORT_RETURN_IF_NOT(onnxruntime::utils::HasExternalData(tensor_proto),
                     "Tensor does not have external data to read from.");
 
-  ORT_RETURN_IF_NOT(tensor_proto.data_type() != ONNX_NAMESPACE::TensorProto_DataType_STRING,
-                    "External data type cannot be UNDEFINED or STRING.");
+  ORT_RETURN_IF(!onnxruntime::utils::HasDataType(tensor_proto) || onnxruntime::utils::HasString(tensor_proto),
+                "External data type cannot be UNDEFINED or STRING.");
 
   std::unique_ptr<onnxruntime::ExternalDataInfo> external_data_info;
   ORT_RETURN_IF_ERROR(onnxruntime::ExternalDataInfo::Create(tensor_proto.external_data(), external_data_info));
@@ -143,7 +143,7 @@ static Status GetExternalDataInfo(const ONNX_NAMESPACE::TensorProto& tensor_prot
   const size_t external_data_length = external_data_info->GetLength();
 
   ORT_RETURN_IF_NOT(external_data_length == 0 || external_data_length == tensor_byte_size,
-                    "TensorProto external data size mismatch. Computed size: ", *&tensor_byte_size,
+                    "TensorProto: ", tensor_proto.name(), " external data size mismatch. Computed size: ", *&tensor_byte_size,
                     ", external_data.length: ", external_data_length);
 
   return Status::OK();
@@ -629,6 +629,16 @@ Status TensorProtoToTensor(const Env& env, const ORTCHAR_T* model_path,
         tensor_proto_dir.size() == 0 ? nullptr : tensor_proto_dir.c_str(),
         external_data_file_path, file_offset, raw_data_len));
 
+    size_t file_length;
+    ORT_RETURN_IF_ERROR(env.GetFileLength(external_data_file_path.c_str(), file_length));
+
+    SafeInt<FileOffsetType> end_of_read(file_offset);
+    end_of_read += raw_data_len;
+    ORT_RETURN_IF(file_offset < 0 || end_of_read > gsl::narrow<FileOffsetType>(file_length),
+                  "External initializer: ", tensor_proto.name(),
+                  " offset: ", file_offset, " size to read: ", static_cast<size_t>(raw_data_len), " given file_length: ", file_length,
+                  " are out of bounds or can not be read in full.");
+
     // load the file
     ORT_RETURN_IF_ERROR(GetFileContent(
         env, external_data_file_path.c_str(), file_offset, raw_data_len,
diff --git a/onnxruntime/core/framework/tensorprotoutils.h b/onnxruntime/core/framework/tensorprotoutils.h
index 8b8a3d6ed0..bb60677297 100644
--- a/onnxruntime/core/framework/tensorprotoutils.h
+++ b/onnxruntime/core/framework/tensorprotoutils.h
@@ -294,6 +294,10 @@ inline bool HasDataType(const ONNX_NAMESPACE::TensorProto& ten_proto) {
   return ten_proto.data_type() != ONNX_NAMESPACE::TensorProto::UNDEFINED;
 }
 
+inline bool HasString(const ONNX_NAMESPACE::TensorProto& ten_proto) {
+  return ten_proto.data_type() == ONNX_NAMESPACE::TensorProto_DataType::TensorProto_DataType_STRING;
+}
+
 #ifndef SHARED_PROVIDER
 inline bool HasName(const ONNX_NAMESPACE::TensorProto& ten_proto) {
   return ten_proto.has_name();  // XXX
diff --git a/onnxruntime/core/graph/graph.cc b/onnxruntime/core/graph/graph.cc
index 6e56dffad3..a5a0bc67e8 100644
--- a/onnxruntime/core/graph/graph.cc
+++ b/onnxruntime/core/graph/graph.cc
@@ -12,6 +12,7 @@
 
 #include "gsl/gsl"
 #include "core/common/logging/logging.h"
+#include "core/common/inlined_containers.h"
 #include "core/flatbuffers/flatbuffers_utils.h"
 #include "core/flatbuffers/schema/ort.fbs.h"
 #include "core/framework/tensor_shape.h"
@@ -2885,7 +2886,7 @@ void Graph::RemoveInitializedTensor(const std::string& tensor_name) {
 }
 
 #if !defined(ORT_MINIMAL_BUILD)
-Status Graph::ReplaceInitializedTensor(const ONNX_NAMESPACE::TensorProto& new_initializer) {
+Status Graph::ReplaceInitializedTensorImpl(ONNX_NAMESPACE::TensorProto new_initializer, bool is_external) {
   // name_to_initial_tensor_ maps from name to const TensorProto*, so we first
   // look up the const pointer by name, then find and modify the mutable
   // pointed-to TensorProto in graph_proto_.
@@ -2904,6 +2905,8 @@ Status Graph::ReplaceInitializedTensor(const ONNX_NAMESPACE::TensorProto& new_in
     return true;
   };
 
+  ORT_RETURN_IF_NOT(!is_external || utils::HasExternalData(old_initializer), "Trying to replace non-external initializer with external data");
+
   ORT_RETURN_IF_NOT(dims_eq(), "Replacement tensor's dimensions do not match.");
   ORT_RETURN_IF_NOT(old_initializer.data_type() == new_initializer.data_type(),
                     "Replacement tensor's data type does not match.");
@@ -2917,10 +2920,28 @@ Status Graph::ReplaceInitializedTensor(const ONNX_NAMESPACE::TensorProto& new_in
   ORT_ENFORCE(existing_entry != mutable_initializers.pointer_end(),
               "graph_proto_ is not in sync with name_to_initial_tensor_");
 
-  **existing_entry = new_initializer;
+  **existing_entry = std::move(new_initializer);
 
   return Status::OK();
 }
+
+Status Graph::ReplaceInitializedTensor(ONNX_NAMESPACE::TensorProto new_initializer) {
+  return ReplaceInitializedTensorImpl(std::move(new_initializer), false);
+}
+
+#if !defined(DISABLE_EXTERNAL_INITIALIZERS)
+Status Graph::InjectExternalInitializedTensors(const InlinedHashMap<std::string, OrtValue>& external_initializers) {
+  for (const auto& e : external_initializers) {
+    const auto& name = e.first;
+    const OrtValue& ort_value = e.second;
+    auto tensor_proto = utils::TensorToTensorProto(ort_value.Get<Tensor>(), name);
+    ORT_RETURN_IF_ERROR(ReplaceInitializedTensorImpl(std::move(tensor_proto), true));
+    LOGS(logger_, INFO) << "Replaced external initializer: " << name;
+  }
+  return Status::OK();
+}
+#endif // DISABLE_EXTERNAL_INITIALIZERS
+
 #endif  // !defined(ORT_MINIMAL_BUILD)
 
 bool Graph::GetInitializedTensor(const std::string& tensor_name, const TensorProto*& value) const {
diff --git a/onnxruntime/core/optimizer/nchwc_transformer.cc b/onnxruntime/core/optimizer/nchwc_transformer.cc
index 57eb1e9ef1..6a41d7b3e3 100644
--- a/onnxruntime/core/optimizer/nchwc_transformer.cc
+++ b/onnxruntime/core/optimizer/nchwc_transformer.cc
@@ -409,7 +409,7 @@ void NchwcTransformerImpl::TransformConv(Node& node) {
     nchwc_conv_W_arg = filters_it->second;
   } else {
     Initializer conv_W{*conv_W_tensor_proto, graph_.ModelPath()};
-    const auto& conv_W_dims = conv_W.dims();
+    const auto conv_W_dims = conv_W.dims();
 
     int64_t reordered_filter_size = nchwc_output_channels * filter_input_channels;
     for (size_t i = 2; i < 4; i++) {
diff --git a/onnxruntime/core/session/abi_session_options.cc b/onnxruntime/core/session/abi_session_options.cc
index cb721b65f8..d8aadcdb7d 100644
--- a/onnxruntime/core/session/abi_session_options.cc
+++ b/onnxruntime/core/session/abi_session_options.cc
@@ -3,6 +3,7 @@
 
 #include "core/graph/onnx_protobuf.h"
 #include "core/common/gsl_suppress.h"
+#include "core/common/inlined_containers.h"
 #include "core/session/onnxruntime_c_api.h"
 #include "core/session/ort_apis.h"
 #include "core/framework/error_code_helper.h"
@@ -177,9 +178,47 @@ ORT_API_STATUS_IMPL(OrtApis::AddSessionConfigEntry, _Inout_ OrtSessionOptions* o
 
 ORT_API_STATUS_IMPL(OrtApis::AddInitializer, _Inout_ OrtSessionOptions* options, _In_z_ const char* name,
                     _In_ const OrtValue* val) {
+  API_IMPL_BEGIN
   auto st = options->value.AddInitializer(name, val);
   if (!st.IsOK()) {
     return onnxruntime::ToOrtStatus(st);
   }
   return nullptr;
-}
\ No newline at end of file
+  API_IMPL_END
+}
+
+ORT_API_STATUS_IMPL(OrtApis::AddExternalInitializers, _In_ OrtSessionOptions* options,
+                    _In_reads_(input_len) const char* const* initializer_names,
+                    _In_reads_(input_len) const OrtValue* const* initializers, size_t initializers_num) {
+
+#if !defined(ORT_MINIMAL_BUILD) && !defined(DISABLE_EXTERNAL_INITIALIZERS)
+  API_IMPL_BEGIN
+  onnxruntime::InlinedVector<std::string> names;
+  onnxruntime::InlinedVector<OrtValue> values;
+  names.reserve(initializers_num);
+  values.reserve(initializers_num);
+  for (size_t i = 0; i < initializers_num; ++i) {
+    if (initializer_names[i] == nullptr || initializers[i] == nullptr) {
+      auto message = onnxruntime::MakeString("Input index: ", i, " contains null pointers");
+      return OrtApis::CreateStatus(ORT_INVALID_ARGUMENT, message.c_str());
+    }
+    names.emplace_back(initializer_names[i]);
+    values.emplace_back(*initializers[i]);
+  }
+
+  auto st = options->value.AddExternalInitializers(names, values);
+  if (!st.IsOK()) {
+    return onnxruntime::ToOrtStatus(st);
+  }
+  return nullptr;
+  API_IMPL_END
+#else
+  ORT_UNUSED_PARAMETER(options);
+  ORT_UNUSED_PARAMETER(initializer_names);
+  ORT_UNUSED_PARAMETER(initializers);
+  ORT_UNUSED_PARAMETER(initializers_num);
+  return OrtApis::CreateStatus(ORT_NOT_IMPLEMENTED, "External initializers are not supported in this build");
+#endif
+}
+
+
diff --git a/onnxruntime/core/session/inference_session.cc b/onnxruntime/core/session/inference_session.cc
index aec976888e..24870d9403 100644
--- a/onnxruntime/core/session/inference_session.cc
+++ b/onnxruntime/core/session/inference_session.cc
@@ -1237,6 +1237,13 @@ common::Status InferenceSession::Initialize() {
     // re-acquire mutex
     std::lock_guard<onnxruntime::OrtMutex> l(session_mutex_);
 
+#if !defined(DISABLE_EXTERNAL_INITIALIZERS) && !defined(ORT_MINIMAL_BUILD)
+    if (!session_options_.external_initializers.empty()) {
+      ORT_RETURN_IF_ERROR_SESSIONID_(graph.InjectExternalInitializedTensors(session_options_.external_initializers));
+      InlinedHashMap<std::string, OrtValue>{}.swap(session_options_.external_initializers);
+    }
+#endif
+
     // At this time we know all the providers that will be part of this session.
     // Read shared allocators from the environment and update them in the respective providers.
     //
diff --git a/onnxruntime/core/session/onnxruntime_c_api.cc b/onnxruntime/core/session/onnxruntime_c_api.cc
index 2a3800488a..fe8580f1a0 100644
--- a/onnxruntime/core/session/onnxruntime_c_api.cc
+++ b/onnxruntime/core/session/onnxruntime_c_api.cc
@@ -2521,6 +2521,7 @@ static constexpr OrtApi ort_api_1_to_12 = {
     &OrtApis::ReleaseCUDAProviderOptions,
     &OrtApis::SessionOptionsAppendExecutionProvider_MIGraphX,
     // End of Version 11 - DO NOT MODIFY ABOVE (see above text for more information)
+    &OrtApis::AddExternalInitializers,
 };
 
 // Asserts to do a some checks to ensure older Versions of the OrtApi never change (will detect an addition or deletion but not if they cancel out each other)
diff --git a/onnxruntime/core/session/ort_apis.h b/onnxruntime/core/session/ort_apis.h
index c93f2cd33f..511255c81c 100644
--- a/onnxruntime/core/session/ort_apis.h
+++ b/onnxruntime/core/session/ort_apis.h
@@ -339,4 +339,8 @@ ORT_API_STATUS_IMPL(UpdateCUDAProviderOptions, _Inout_ OrtCUDAProviderOptionsV2*
                     size_t num_keys);
 ORT_API_STATUS_IMPL(GetCUDAProviderOptionsAsString, _In_ const OrtCUDAProviderOptionsV2* cuda_options, _Inout_ OrtAllocator* allocator, _Outptr_ char** ptr);
 ORT_API(void, ReleaseCUDAProviderOptions, _Frees_ptr_opt_ OrtCUDAProviderOptionsV2*);
+ORT_API_STATUS_IMPL(AddExternalInitializers, _In_ OrtSessionOptions* options,
+                    _In_reads_(input_len) const char* const* input_names,
+                    _In_reads_(input_len) const OrtValue* const* inputs, size_t input_len);
+
 }  // namespace OrtApis
diff --git a/onnxruntime/python/onnxruntime_pybind_state.cc b/onnxruntime/python/onnxruntime_pybind_state.cc
index 5b11bf1bc5..b255b26552 100644
--- a/onnxruntime/python/onnxruntime_pybind_state.cc
+++ b/onnxruntime/python/onnxruntime_pybind_state.cc
@@ -9,6 +9,7 @@
 #define PY_ARRAY_UNIQUE_SYMBOL onnxruntime_python_ARRAY_API
 #include <numpy/arrayobject.h>
 
+#include "core/common/inlined_containers.h"
 #include "core/common/logging/logging.h"
 #include "core/common/logging/severity.h"
 #include "core/common/optional.h"
@@ -1234,7 +1235,28 @@ Applies to session load, initialization, etc. Default is 0.)pbdoc")
             // This is no different than the native APIs
             const OrtValue* ml_value = ml_value_pyobject.attr(PYTHON_ORTVALUE_NATIVE_OBJECT_ATTR).cast<OrtValue*>();
             ORT_THROW_IF_ERROR(options->AddInitializer(name, ml_value));
-          });
+          })
+      .def("add_external_initializers", [](PySessionOptions* options, py::list& names, 
+                                                    const py::list& ort_values) -> void {
+#if !defined(ORT_MINIMAL_BUILD) && !defined(DISABLE_EXTERNAL_INITIALIZERS)
+          const auto init_num = ort_values.size();
+          ORT_ENFORCE(init_num == names.size(), "Expecting names and ort_values lists to have equal length");
+          InlinedVector<std::string> names_ptrs;
+          InlinedVector<OrtValue> values_ptrs;
+          names_ptrs.reserve(init_num);
+          values_ptrs.reserve(init_num);
+          for (size_t i = 0; i < init_num; ++i) {
+            names_ptrs.emplace_back(py::str(names[i]));
+            values_ptrs.emplace_back(*ort_values[i].attr(PYTHON_ORTVALUE_NATIVE_OBJECT_ATTR).cast<const OrtValue*>());
+          }
+          ORT_THROW_IF_ERROR(options->AddExternalInitializers(names_ptrs, values_ptrs));
+#else
+          ORT_UNUSED_PARAMETER(options);
+          ORT_UNUSED_PARAMETER(names);
+          ORT_UNUSED_PARAMETER(ort_values);
+          ORT_THROW("External initializers are not supported in this build.");
+#endif
+      });
 
   py::class_<RunOptions>(m, "RunOptions", R"pbdoc(Configuration information for a single Run.)pbdoc")
       .def(py::init())
diff --git a/onnxruntime/test/ir/graph_test.cc b/onnxruntime/test/ir/graph_test.cc
index 96b725c755..36d6fb9b6b 100644
--- a/onnxruntime/test/ir/graph_test.cc
+++ b/onnxruntime/test/ir/graph_test.cc
@@ -2,6 +2,8 @@
 // Licensed under the MIT License.
 
 #include <iostream>
+#include "core/common/inlined_containers.h"
+#include "core/framework/tensorprotoutils.h"
 #include "core/graph/graph_viewer.h"
 #include "core/graph/model.h"
 #include "core/graph/op.h"
@@ -1697,7 +1699,7 @@ TEST_F(GraphTest, ReplaceInitializedTensor) {
     ONNX_NAMESPACE::TensorProto bad_name = original;
     bad_name.set_name("invalid");
 
-    status = graph.ReplaceInitializedTensor(bad_name);
+    status = graph.ReplaceInitializedTensor(std::move(bad_name));
     ASSERT_FALSE(status.IsOK());
   }
 
@@ -1705,7 +1707,7 @@ TEST_F(GraphTest, ReplaceInitializedTensor) {
     ONNX_NAMESPACE::TensorProto bad_type = original;
     bad_type.set_data_type(TensorProto_DataType_FLOAT16);
 
-    status = graph.ReplaceInitializedTensor(bad_type);
+    status = graph.ReplaceInitializedTensor(std::move(bad_type));
     ASSERT_FALSE(status.IsOK());
   }
 
@@ -1715,7 +1717,7 @@ TEST_F(GraphTest, ReplaceInitializedTensor) {
     bad_dims.add_dims(2);
     bad_dims.add_dims(1);
 
-    status = graph.ReplaceInitializedTensor(bad_dims);
+    status = graph.ReplaceInitializedTensor(std::move(bad_dims));
     ASSERT_FALSE(status.IsOK());
   }
 
@@ -1748,6 +1750,88 @@ TEST_F(GraphTest, ReplaceInitializedTensor) {
   }
 }
 
+#if !defined(ORT_MINIMAL_BUILD) && !defined(DISABLE_EXTERNAL_INITIALIZERS)
+
+namespace {
+void SetTensorProtoExternalData(const std::string& key, const std::string& value,
+                                ONNX_NAMESPACE::TensorProto& tensor_proto) {
+  auto* external_data = tensor_proto.mutable_external_data();
+  auto kvp_it = std::find_if(
+      external_data->begin(), external_data->end(),
+      [&key](const ONNX_NAMESPACE::StringStringEntryProto& kvp) { return kvp.key() == key; });
+  auto* kvp = kvp_it != external_data->end() ? &(*kvp_it) : external_data->Add();
+  kvp->set_key(key);
+  kvp->set_value(value);
+}
+}  // namespace
+
+TEST_F(GraphTest, InjectExternalInitializedTensors) {
+  const std::string initializer_name = "test_external_initializer";
+
+  std::vector<int32_t> tensor_data = []() {
+    std::vector<int32_t> tensor_data(100);
+    std::iota(tensor_data.begin(), tensor_data.end(), 0);
+    return tensor_data;
+  }();
+
+  // Create OrtValue for replacement
+  TensorShape data_shape{static_cast<int64_t>(tensor_data.size())};
+  OrtValue ort_value;
+  Tensor::InitOrtValue(DataTypeImpl::GetType<int32_t>(), data_shape, tensor_data.data(),
+                       OrtMemoryInfo(onnxruntime::CPU, OrtAllocatorType::OrtDeviceAllocator), ort_value);
+  const InlinedHashMap<std::string, OrtValue> injection_initializers = {
+      {initializer_name, ort_value}
+  };
+
+  // We do not need actual files there since we are not going to load it.
+  const auto tensor_data_dir_path = Path::Parse(ToPathString("."));
+  const auto tensor_data_dir_relative_path = Path::Parse(ToPathString("external_data.bin"));
+
+  const auto tensor_proto =
+      [&]() {
+        ONNX_NAMESPACE::TensorProto tensor_proto;
+        tensor_proto.set_name(initializer_name);
+        tensor_proto.add_dims(tensor_data.size());
+        tensor_proto.set_data_type(ONNX_NAMESPACE::TensorProto_DataType_INT32);
+        tensor_proto.set_data_location(ONNX_NAMESPACE::TensorProto_DataLocation_EXTERNAL);
+        SetTensorProtoExternalData("location", ToUTF8String(tensor_data_dir_relative_path.ToPathString()), tensor_proto);
+        SetTensorProtoExternalData("offset", "0", tensor_proto);
+        SetTensorProtoExternalData("length", std::to_string(tensor_data.size() * sizeof(int32_t)), tensor_proto);
+        return tensor_proto;
+      }();
+
+  Model m{"test_model", false, *logger_};
+  Graph& graph = m.MainGraph();
+  graph.AddInitializedTensor(tensor_proto);
+
+  ASSERT_EQ(graph.GetAllInitializedTensors().size(), 1U);
+
+  const TensorProto* external_data = nullptr;
+  ASSERT_TRUE(graph.GetInitializedTensor(initializer_name, external_data));
+  ASSERT_TRUE(utils::HasExternalData(*external_data));
+
+  // Replace things.
+  ASSERT_STATUS_OK(graph.InjectExternalInitializedTensors(injection_initializers));
+
+  ASSERT_EQ(graph.GetAllInitializedTensors().size(), 1U);
+
+  const TensorProto* with_data = nullptr;
+  ASSERT_TRUE(graph.GetInitializedTensor(initializer_name, with_data));
+  // No longer has external data
+  ASSERT_FALSE(utils::HasExternalData(*with_data));
+
+  const auto& original_tensor = ort_value.Get<Tensor>();
+
+  Tensor replaced_tensor(original_tensor.DataType(), data_shape, std::make_shared<CPUAllocator>());
+  ASSERT_STATUS_OK(utils::TensorProtoToTensor(Env::Default(), tensor_data_dir_path.ToPathString().c_str(), *with_data, replaced_tensor));
+
+  ASSERT_EQ(original_tensor.GetElementType(), replaced_tensor.GetElementType());
+  const auto original_span = original_tensor.DataAsSpan<int32_t>();
+  const auto replaced_span = replaced_tensor.DataAsSpan<int32_t>();
+  ASSERT_EQ(original_span, replaced_span);
+}
+#endif
+
 TEST_F(GraphTest, AddRemoveInitializerHandling) {
   Model m{"test_model", false, *logger_};
   Graph& graph = m.MainGraph();
diff --git a/onnxruntime/test/python/onnxruntime_test_python.py b/onnxruntime/test/python/onnxruntime_test_python.py
index 858f18c97e..8f29c974f9 100644
--- a/onnxruntime/test/python/onnxruntime_test_python.py
+++ b/onnxruntime/test/python/onnxruntime_test_python.py
@@ -827,6 +827,16 @@ class TestInferenceSession(unittest.TestCase):
         res = sess.run(["Y"], {"X": np.array([[1.0, 2.0], [3.0, 4.0], [5.0, 6.0]], dtype=np.float32)})
         self.assertTrue(np.array_equal(res[0], np.array([[2.0, 2.0], [12.0, 12.0], [30.0, 30.0]], dtype=np.float32)))
 
+    def testSessionOptionsAddExternalInitializers(self):
+        # Create an external initializer data in OrtValue
+        # This initializer will replace the initializer with external data reference in the graph
+        ortvalue_initializer = onnxrt.OrtValue.ortvalue_from_numpy(np.array([0, 0, 1, 1]).astype(np.int64))
+        so = onnxrt.SessionOptions()
+        so.add_external_initializers(["Pads_not_on_disk"], [ortvalue_initializer])
+        # This should not throw
+        onnxrt.InferenceSession(get_name("model_with_external_initializer_come_from_user.onnx"), sess_options=so, providers=['CPUExecutionProvider'])
+
+
     def testRegisterCustomOpsLibrary(self):
         if sys.platform.startswith("win"):
             shared_library = 'custom_op_library.dll'
diff --git a/onnxruntime/test/shared_lib/test_model_loading.cc b/onnxruntime/test/shared_lib/test_model_loading.cc
index 9457cf9029..5324b1ffb8 100644
--- a/onnxruntime/test/shared_lib/test_model_loading.cc
+++ b/onnxruntime/test/shared_lib/test_model_loading.cc
@@ -60,7 +60,7 @@ TEST(CApiTest, model_from_array) {
 #ifdef DISABLE_EXTERNAL_INITIALIZERS
 TEST(CApiTest, TestDisableExternalInitiliazers) {
 
-  const char* model_path = "testdata/model_with_external_initializers.onnx";
+  constexpr auto model_path = ORT_TSTR("testdata/model_with_external_initializers.onnx");
 
   Ort::SessionOptions so;
   try {
@@ -70,6 +70,25 @@ TEST(CApiTest, TestDisableExternalInitiliazers) {
     ASSERT_THAT(ex.what(), testing::HasSubstr("Initializer tensors with external data is not allowed."));
   }
 }
+
+#elif !defined(ORT_MINIMAL_BUILD)
+TEST(CApiTest, TestExternalInitializersInjection) {
+  constexpr auto model_path = ORT_TSTR("testdata/model_with_external_initializer_come_from_user.onnx");
+  std::array<int64_t, 4> Pads_not_on_disk{0, 0, 1, 1};
+  constexpr std::array<int64_t, 1> init_shape{4};
+
+  const std::vector<std::string> init_names{"Pads_not_on_disk"};
+  std::vector<Ort::Value> initializer_data;
+
+  auto cpu_mem_info = Ort::MemoryInfo::CreateCpu(OrtDeviceAllocator, OrtMemTypeCPU);
+  auto init_tensor = Ort::Value::CreateTensor(cpu_mem_info, Pads_not_on_disk.data(), Pads_not_on_disk.size(), init_shape.data(), init_shape.size());
+  initializer_data.push_back(std::move(init_tensor));
+
+  Ort::SessionOptions so;
+  so.AddExternalInitializers(init_names, initializer_data);
+  EXPECT_NO_THROW(Ort::Session(*ort_env, model_path, so));
+}
+
 #endif
 }  // namespace test
 }  // namespace onnxruntime
diff --git a/onnxruntime/test/testdata/model_with_external_initializer_come_from_user.onnx b/onnxruntime/test/testdata/model_with_external_initializer_come_from_user.onnx
new file mode 100644
index 0000000000..486573918e
--- /dev/null
+++ b/onnxruntime/test/testdata/model_with_external_initializer_come_from_user.onnx
@@ -0,0 +1,19 @@
+onnx-example:Æ

+2
+
X
+Pads_not_on_disk
Y"Pad*
+mode"constant 

+test-model*:BPads_not_on_diskj 
+locationPads_not_on_disk.binp
Z
+
X
+

+

+Z
+Pads_not_on_disk
+
+
+b
+
Y
+

+

+B
\ No newline at end of file
diff --git a/onnxruntime/test/testdata/model_with_external_initializer_come_from_user.py b/onnxruntime/test/testdata/model_with_external_initializer_come_from_user.py
new file mode 100644
index 0000000000..baad806b7e
--- /dev/null
+++ b/onnxruntime/test/testdata/model_with_external_initializer_come_from_user.py
@@ -0,0 +1,62 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+import onnx
+import numpy as np
+from onnx import helper
+from onnx import TensorProto
+from onnx.numpy_helper import from_array
+from onnx.external_data_helper import set_external_data
+
+
+def create_external_data_tensor(value, tensor_name):  # type: (List[Any], Text) -> TensorProto
+    tensor = from_array(value)
+    tensor.name = tensor_name
+    tensor_filename = "{}.bin".format(tensor_name)
+    set_external_data(tensor, location=tensor_filename)
+    tensor.ClearField('raw_data')
+    tensor.data_location = onnx.TensorProto.EXTERNAL
+    return tensor
+
+
+def GenerateModel(model_name):
+    # Create one input (ValueInfoProto)
+    X = helper.make_tensor_value_info('X', TensorProto.FLOAT, [1, 2])
+
+    # Create second input (ValueInfoProto)
+    Pads = helper.make_tensor_value_info('Pads_not_on_disk', TensorProto.INT64, [4])
+
+    # Create one output (ValueInfoProto)
+    Y = helper.make_tensor_value_info('Y', TensorProto.FLOAT, [1, 4])
+
+    # Create a node (NodeProto)
+    node_def = helper.make_node(
+        'Pad', # node name
+        ['X', 'Pads_not_on_disk'], # inputs
+        ['Y'], # outputs
+        mode='constant', # Attributes
+    )
+
+    # Create the graph (GraphProto)
+    initializer_data = np.array([0, 0, 1, 1]).astype(np.int64)
+    graph_def = helper.make_graph(
+        [node_def],
+        "test-model",
+        [X, Pads],
+        [Y],
+        [create_external_data_tensor(initializer_data, "Pads_not_on_disk")]
+    )
+
+    # Create the model (ModelProto)
+    model_def = helper.make_model(graph_def,
+                                  producer_name='onnx-example')
+
+    print('The ir_version in model: {}\n'.format(model_def.ir_version))
+    print('The producer_name in model: {}\n'.format(model_def.producer_name))
+    print('The graph in model:\n{}'.format(model_def.graph))
+    with open(model_name, "wb") as model_file:
+        model_file.write(model_def.SerializeToString())
+
+
+if __name__ == "__main__":
+    GenerateModel('model_with_external_initializer_come_from_user.onnx')
diff --git a/orttraining/orttraining/models/bert/main.cc b/orttraining/orttraining/models/bert/main.cc
index 2c303086c0..18004ef4bc 100644
--- a/orttraining/orttraining/models/bert/main.cc
+++ b/orttraining/orttraining/models/bert/main.cc
@@ -58,7 +58,8 @@ static SessionOptions session_options = {
     true,                              //thread_pool_allow_spinning
     false,                             //use_deterministic_compute
     {},                                //config_options
-    {},                                // initializers_to_share_map
+    {},                                //initializers_to_share_map
+    {},                                // external_initializers
 };
 
 struct BertParameters : public TrainingRunner::Parameters {
diff --git a/orttraining/orttraining/models/pipeline_poc/main.cc b/orttraining/orttraining/models/pipeline_poc/main.cc
index 0e4fe1716d..25f7180be2 100644
--- a/orttraining/orttraining/models/pipeline_poc/main.cc
+++ b/orttraining/orttraining/models/pipeline_poc/main.cc
@@ -108,7 +108,8 @@ int main(int argc, char* argv[]) {
       true,                              //thread_pool_allow_spinning
       false,                             //use_deterministic_compute
       {},                                //session_configurations
-      {}                                 //initializers_to_share_map
+      {},                                //initializers_to_share_map
+      {}                                 // external_initializers
   };
 
   InferenceSession session_object{so, *env};
diff --git a/orttraining/orttraining/models/runner/training_runner.cc b/orttraining/orttraining/models/runner/training_runner.cc
index 664b489c62..b97ffc6f41 100644
--- a/orttraining/orttraining/models/runner/training_runner.cc
+++ b/orttraining/orttraining/models/runner/training_runner.cc
@@ -55,6 +55,7 @@ static SessionOptions SESSION_OPTION = {
     false,                             //use_deterministic_compute
     {},                                //config_options
     {},                                // initializers_to_share_map
+    {},                                // external_initializers
 };
 
 TrainingRunner::TrainingRunner(Parameters params, const Environment& env)