diff --git a/onnxruntime/core/graph/model.cc b/onnxruntime/core/graph/model.cc
index 3cc756a12a..8b43d7356b 100644
--- a/onnxruntime/core/graph/model.cc
+++ b/onnxruntime/core/graph/model.cc
@@ -96,7 +96,7 @@ Model::Model(std::unique_ptr<ModelProto> model_proto, const IOnnxRuntimeOpSchema
   }
 
   if (!model_proto->has_ir_version() || model_proto->ir_version() > ONNX_NAMESPACE::Version::IR_VERSION) {
-      throw std::invalid_argument("Unknown model file format version.");
+    throw std::invalid_argument("Unknown model file format version.");
   }
 
   model_proto_ = std::move(model_proto);
@@ -394,14 +394,14 @@ Status Model::LoadFromBytes(int count, void* p_bytes, /*out*/ ONNX_NAMESPACE::Mo
 
 Status Model::LoadFromBytes(int count, void* p_bytes, /*out*/ std::shared_ptr<Model>& p_model,
                             const IOnnxRuntimeOpSchemaRegistryList* local_registries, const logging::Logger& logger) {
-  ModelProto model_proto;
+  auto model_proto = onnxruntime::make_unique<ModelProto>();
 
-  auto status = LoadFromBytes(count, p_bytes, model_proto);
+  auto status = LoadFromBytes(count, p_bytes, *model_proto);
   if (!status.IsOK()) {
     return status;
   }
 
-  p_model = std::make_shared<Model>(model_proto, local_registries, logger);
+  p_model = std::make_shared<Model>(std::move(model_proto), local_registries, logger);
 
   ORT_RETURN_IF_ERROR(p_model->MainGraph().Resolve(true));
 
@@ -441,11 +441,11 @@ Status Model::Load(int fd, ONNX_NAMESPACE::ModelProto& model_proto) {
 
 Status Model::Load(int fd, std::shared_ptr<Model>& p_model, const IOnnxRuntimeOpSchemaRegistryList* local_registries,
                    const logging::Logger& logger) {
-  ModelProto model_proto;
+  auto model_proto = onnxruntime::make_unique<ModelProto>();
 
-  ORT_RETURN_IF_ERROR(Load(fd, model_proto));
+  ORT_RETURN_IF_ERROR(Load(fd, *model_proto));
 
-  p_model = std::make_shared<Model>(model_proto, local_registries, logger);
+  p_model = std::make_shared<Model>(std::move(model_proto), local_registries, logger);
 
   ORT_RETURN_IF_ERROR(p_model->MainGraph().Resolve(true));
 
diff --git a/onnxruntime/core/session/inference_session.cc b/onnxruntime/core/session/inference_session.cc
index 8f46e9ee16..651a2eee18 100644
--- a/onnxruntime/core/session/inference_session.cc
+++ b/onnxruntime/core/session/inference_session.cc
@@ -372,9 +372,10 @@ common::Status InferenceSession::Load(std::function<common::Status(std::shared_p
     // all steps complete, mark the model as loaded.
     is_model_loaded_ = true;
 
-    // since model load was successful, we don't need to hang on to the member 'model_proto_' anymore
-    // (free up the resource if applicable - if the unique_ptr is a nullptr, reset() doesn't do anything)
-    model_proto_.reset();
+    // model_proto_ should either - 1) always have been a nullptr if the ModelProto was never parsed in the ctor (or)
+    // 2) should have become a nullptr by passing on the ownership of the ModelProto resource it was pointing to,
+    // to the Model instance
+    ORT_ENFORCE(model_proto_ == nullptr, "Failed to clear up model_proto_ in Inference Session");
 
     telemetry_.event_name_ = event_name;
 
@@ -451,6 +452,7 @@ common::Status InferenceSession::Load(const ModelProto& model_proto) {
       AddCustomOpDomains({domain.get()});
     }
 #endif
+    // This call will create a copy of model_proto and the constructed model instance will own the copy thereafter
     return onnxruntime::Model::Load(model_proto, model, HasLocalSchema() ? &custom_schema_registries_ : nullptr,
                                     *session_logger_);
   };
@@ -487,21 +489,21 @@ common::Status InferenceSession::Load(std::istream& model_istream) {
   }
 
   auto loader = [this, &model_istream](std::shared_ptr<onnxruntime::Model>& model) {
-    ModelProto model_proto;
+    auto model_proto = onnxruntime::make_unique<ONNX_NAMESPACE::ModelProto>();
 
     google::protobuf::io::IstreamInputStream zero_copy_input(&model_istream);
-    const bool result = model_proto.ParseFromZeroCopyStream(&zero_copy_input) && model_istream.eof();
+    const bool result = model_proto->ParseFromZeroCopyStream(&zero_copy_input) && model_istream.eof();
     if (!result) {
       return Status(common::ONNXRUNTIME, common::INVALID_PROTOBUF,
                     "Failed to load model because protobuf parsing failed.");
     }
 #ifdef ENABLE_LANGUAGE_INTEROP_OPS
-    LoadInterOp(model_proto, interop_domains_, [&](const char* msg) { LOGS(*session_logger_, WARNING) << msg; });
+    LoadInterOp(*model_proto, interop_domains_, [&](const char* msg) { LOGS(*session_logger_, WARNING) << msg; });
     for (const auto& domain : interop_domains_) {
       AddCustomOpDomains({domain.get()});
     }
 #endif
-    return onnxruntime::Model::Load(model_proto, model, HasLocalSchema() ? &custom_schema_registries_ : nullptr,
+    return onnxruntime::Model::Load(std::move(model_proto), model, HasLocalSchema() ? &custom_schema_registries_ : nullptr,
                                     *session_logger_);
   };
 
@@ -516,21 +518,21 @@ common::Status InferenceSession::Load(const void* model_data, int model_data_len
   }
 
   auto loader = [this, model_data, model_data_len](std::shared_ptr<onnxruntime::Model>& model) {
-    ModelProto model_proto;
+    auto model_proto = onnxruntime::make_unique<ONNX_NAMESPACE::ModelProto>();
 
-    const bool result = model_proto.ParseFromArray(model_data, model_data_len);
+    const bool result = model_proto->ParseFromArray(model_data, model_data_len);
     if (!result) {
       return Status(common::ONNXRUNTIME, common::INVALID_PROTOBUF,
                     "Failed to load model because protobuf parsing failed.");
     }
 #ifdef ENABLE_LANGUAGE_INTEROP_OPS
-    LoadInterOp(model_proto, interop_domains_, [&](const char* msg) { LOGS(*session_logger_, WARNING) << msg; });
+    LoadInterOp(*model_proto, interop_domains_, [&](const char* msg) { LOGS(*session_logger_, WARNING) << msg; });
     for (const auto& domain : interop_domains_) {
       AddCustomOpDomains({domain.get()});
     }
 #endif
 
-    return onnxruntime::Model::Load(model_proto, model, HasLocalSchema() ? &custom_schema_registries_ : nullptr,
+    return onnxruntime::Model::Load(std::move(model_proto), model, HasLocalSchema() ? &custom_schema_registries_ : nullptr,
                                     *session_logger_);
   };
 
@@ -551,7 +553,8 @@ common::Status InferenceSession::Load() {
       AddCustomOpDomains({domain.get()});
     }
 #endif
-    return Model::Load(*this->model_proto_, model, HasLocalSchema() ? &custom_schema_registries_ : nullptr,
+    // Pass on ownership of the parsed ModelProto to the Model instance (its job here is done by this stage)
+    return Model::Load(std::move(this->model_proto_), model, HasLocalSchema() ? &custom_schema_registries_ : nullptr,
                        *session_logger_);
   };