diff --git a/cmake/onnxruntime_unittests.cmake b/cmake/onnxruntime_unittests.cmake
index 988b98fb29d48..b4688abe97b24 100644
--- a/cmake/onnxruntime_unittests.cmake
+++ b/cmake/onnxruntime_unittests.cmake
@@ -590,6 +590,7 @@ set (onnxruntime_shared_lib_test_SRC
           ${ONNXRUNTIME_SHARED_LIB_TEST_SRC_DIR}/test_run_options.cc
           ${ONNXRUNTIME_SHARED_LIB_TEST_SRC_DIR}/test_runtime_path.cc
           ${ONNXRUNTIME_SHARED_LIB_TEST_SRC_DIR}/test_session_options.cc
+          ${ONNXRUNTIME_SHARED_LIB_TEST_SRC_DIR}/test_version.cc
           ${ONNXRUNTIME_SHARED_LIB_TEST_SRC_DIR}/utils.h
           ${ONNXRUNTIME_SHARED_LIB_TEST_SRC_DIR}/utils.cc
           )
diff --git a/docs/Versioning.md b/docs/Versioning.md
index a8d26f7d74185..904e4f777561e 100644
--- a/docs/Versioning.md
+++ b/docs/Versioning.md
@@ -57,13 +57,19 @@ npm --version    # Should be v8.0 or newer
 
    Replace `X.Y.Z` with your new version number. The comments following this assert explain additional steps if new APIs were added to this release.
 
-4. **Review all changes**
+4. **Update the C API header `ORT_API_VERSION` value (Manual Step)**
+
+   The script does **not** update the value of `ORT_API_VERSION` in [include/onnxruntime/core/session/onnxruntime_c_api.h](../include/onnxruntime/core/session/onnxruntime_c_api.h).
+
+   The value should be set to the second component of the version string. E.g., `25` for version `1.25.0`.
+
+5. **Review all changes**
 
    Review all modified files. Verify:
    - Version numbers are correct in all updated files
    - The release notes URL format is correct (e.g., `https://github.com/Microsoft/onnxruntime/releases/tag/vX.Y.Z`)
 
-5. **Commit and create PR**
+6. **Commit and create PR**
 
    Commit all changes and create a PR targeting `main` or a release branch as appropriate.
 
diff --git a/include/onnxruntime/core/session/onnxruntime_c_api.h b/include/onnxruntime/core/session/onnxruntime_c_api.h
index 221f3673f2027..77c2ff795e800 100644
--- a/include/onnxruntime/core/session/onnxruntime_c_api.h
+++ b/include/onnxruntime/core/session/onnxruntime_c_api.h
@@ -38,7 +38,7 @@
  *
  * This value is used by some API functions to behave as this version of the header expects.
  */
-#define ORT_API_VERSION 24
+#define ORT_API_VERSION 25
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/onnxruntime/test/shared_lib/test_version.cc b/onnxruntime/test/shared_lib/test_version.cc
new file mode 100644
index 0000000000000..5427378e7788a
--- /dev/null
+++ b/onnxruntime/test/shared_lib/test_version.cc
@@ -0,0 +1,31 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+#include "core/session/onnxruntime_cxx_api.h"
+
+#include <cstdint>
+#include <charconv>
+#include <optional>
+#include <string>
+#include <vector>
+
+#include "absl/strings/str_split.h"
+#include "gtest/gtest.h"
+
+TEST(CApiTest, VersionConsistencyWithApiVersion) {
+  const auto version_string = Ort::GetVersionString();
+  const std::vector<std::string> version_string_components = absl::StrSplit(version_string, '.');
+  ASSERT_EQ(version_string_components.size(), size_t{3});
+
+  auto to_uint32_t = [](const std::string& s) -> std::optional<uint32_t> {
+    uint32_t result{};
+    if (std::from_chars(s.data(), s.data() + s.size(), result).ec == std::errc{}) {
+      return result;
+    }
+    return std::nullopt;
+  };
+
+  ASSERT_NE(to_uint32_t(version_string_components[0]), std::nullopt);
+  ASSERT_EQ(to_uint32_t(version_string_components[1]), uint32_t{ORT_API_VERSION});
+  ASSERT_NE(to_uint32_t(version_string_components[0]), std::nullopt);
+}