diff --git a/cmake/onnxruntime_unittests.cmake b/cmake/onnxruntime_unittests.cmake
index 81bb0878f5017..a7344d05bf0fd 100644
--- a/cmake/onnxruntime_unittests.cmake
+++ b/cmake/onnxruntime_unittests.cmake
@@ -1148,6 +1148,15 @@ endif()
 
 partition_provider_test_srcs(all_tests onnxruntime_provider_test_srcs onnxruntime_test_all_srcs)
 
+if (onnxruntime_USE_OPENVINO)
+  # ov_protobuf_utils.cpp lives under core/providers (not test/), so partition_provider_test_srcs
+  # would route it to onnxruntime_test_all. Append it here after the partition so it is compiled into
+  # onnxruntime_provider_test alongside openvino_ov_protobuf_utils_test.cc, because the OpenVINO EP
+  # is a dynamically-loaded module and is not statically linked into the test binary.
+  list(APPEND onnxruntime_provider_test_srcs
+       ${ONNXRUNTIME_ROOT}/core/providers/openvino/ov_protobuf_utils.cpp)
+endif()
+
 # Workarounds for onnxruntime test targets.
 function(onnxruntime_apply_test_target_workarounds target)
   if (MSVC)
diff --git a/onnxruntime/core/providers/openvino/ov_protobuf_utils.cpp b/onnxruntime/core/providers/openvino/ov_protobuf_utils.cpp
index e28330e0bd433..8e4704ab0fb22 100644
--- a/onnxruntime/core/providers/openvino/ov_protobuf_utils.cpp
+++ b/onnxruntime/core/providers/openvino/ov_protobuf_utils.cpp
@@ -3,6 +3,8 @@
 
 #include "ov_protobuf_utils.h"
 
+#include <cstring>
+
 #include "core/graph/onnx_protobuf.h"
 #include "core/common/common.h"
 
@@ -11,14 +13,35 @@ namespace openvino_ep {
 float get_float_initializer_data(const void* initializer) {
   const auto* tp = reinterpret_cast<const ONNX_NAMESPACE::TensorProto*>(initializer);
   ORT_ENFORCE((tp->has_data_type() && (tp->data_type() == ONNX_NAMESPACE::TensorProto_DataType_FLOAT)));
-  // ORT_ENFORCE(initializer.dims_size() == 1);
-  return tp->float_data(0);
+
+  // A FLOAT scalar/tensor may store its value either in the typed float_data
+  // field or in raw_data. Indexing float_data(0) when it is empty is undefined
+  // behavior, so pick the field that actually holds the data.
+  if (tp->float_data_size() > 0) {
+    return tp->float_data(0);
+  }
+
+  ORT_ENFORCE(tp->has_raw_data() && tp->raw_data().size() >= sizeof(float),
+              "FLOAT initializer has neither float_data nor sufficient raw_data to read a value");
+  float value;
+  std::memcpy(&value, tp->raw_data().data(), sizeof(float));
+  return value;
 }
 void set_float_initializer_data(const void* initializer, float data) {
   auto* tp = (ONNX_NAMESPACE::TensorProto*)(initializer);
   ORT_ENFORCE((tp->has_data_type() && (tp->data_type() == ONNX_NAMESPACE::TensorProto_DataType_FLOAT)));
-  // ORT_ENFORCE(initializer.dims_size() == 1);
-  tp->set_float_data(0, data);
+
+  // Mirror get_float_initializer_data: write back into whichever storage the
+  // initializer actually uses. set_float_data(0, data) on an empty float_data
+  // field is an out-of-bounds write.
+  if (tp->float_data_size() > 0) {
+    tp->set_float_data(0, data);
+    return;
+  }
+
+  ORT_ENFORCE(tp->has_raw_data() && tp->raw_data().size() >= sizeof(float),
+              "FLOAT initializer has neither float_data nor sufficient raw_data to write a value");
+  tp->set_raw_data(&data, sizeof(float));
 }
 }  // namespace openvino_ep
 }  // namespace onnxruntime
diff --git a/onnxruntime/test/providers/openvino/openvino_ov_protobuf_utils_test.cc b/onnxruntime/test/providers/openvino/openvino_ov_protobuf_utils_test.cc
new file mode 100644
index 0000000000000..67a5ea7b30cd4
--- /dev/null
+++ b/onnxruntime/test/providers/openvino/openvino_ov_protobuf_utils_test.cc
@@ -0,0 +1,68 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+#include <cstring>
+
+#include "core/graph/onnx_protobuf.h"
+#include "core/providers/openvino/ov_protobuf_utils.h"
+
+#include "gtest/gtest.h"
+
+using namespace ONNX_NAMESPACE;
+
+namespace onnxruntime {
+namespace test {
+
+// Builds a FLOAT scalar whose value lives in raw_data, with an empty float_data
+// field.
+static TensorProto MakeRawDataFloatScalar(float value) {
+  TensorProto tp;
+  tp.set_data_type(TensorProto_DataType_FLOAT);
+  tp.set_raw_data(&value, sizeof(float));
+  return tp;
+}
+
+// Builds a FLOAT scalar whose value lives in the typed float_data field.
+static TensorProto MakeFloatDataScalar(float value) {
+  TensorProto tp;
+  tp.set_data_type(TensorProto_DataType_FLOAT);
+  tp.add_float_data(value);
+  return tp;
+}
+
+TEST(OpenVINO_OvProtobufUtils, GetFromRawData) {
+  TensorProto tp = MakeRawDataFloatScalar(4.0f);
+  ASSERT_EQ(tp.float_data_size(), 0);  // value is only in raw_data
+
+  EXPECT_FLOAT_EQ(openvino_ep::get_float_initializer_data(&tp), 4.0f);
+}
+
+TEST(OpenVINO_OvProtobufUtils, SetIntoRawData) {
+  TensorProto tp = MakeRawDataFloatScalar(4.0f);
+  ASSERT_EQ(tp.float_data_size(), 0);
+
+  openvino_ep::set_float_initializer_data(&tp, 0.5f);
+
+  // The write must land in raw_data (the field that actually holds the value),
+  // and must be readable back through the getter.
+  ASSERT_GE(tp.raw_data().size(), sizeof(float));
+  float stored;
+  std::memcpy(&stored, tp.raw_data().data(), sizeof(float));
+  EXPECT_FLOAT_EQ(stored, 0.5f);
+  EXPECT_FLOAT_EQ(openvino_ep::get_float_initializer_data(&tp), 0.5f);
+}
+
+TEST(OpenVINO_OvProtobufUtils, GetFromFloatData) {
+  TensorProto tp = MakeFloatDataScalar(3.0f);
+  EXPECT_FLOAT_EQ(openvino_ep::get_float_initializer_data(&tp), 3.0f);
+}
+
+TEST(OpenVINO_OvProtobufUtils, SetIntoFloatData) {
+  TensorProto tp = MakeFloatDataScalar(3.0f);
+  openvino_ep::set_float_initializer_data(&tp, 7.0f);
+  EXPECT_FLOAT_EQ(tp.float_data(0), 7.0f);
+  EXPECT_FLOAT_EQ(openvino_ep::get_float_initializer_data(&tp), 7.0f);
+}
+
+}  // namespace test
+}  // namespace onnxruntime