diff --git a/packages/react-native/ReactCommon/hermes/inspector-modern/chrome/tests/HermesRuntimeSamplingProfileSerializerTest.cpp b/packages/react-native/ReactCommon/hermes/inspector-modern/chrome/tests/HermesRuntimeSamplingProfileSerializerTest.cpp
new file mode 100644
index 000000000000..e2cc4361d659
--- /dev/null
+++ b/packages/react-native/ReactCommon/hermes/inspector-modern/chrome/tests/HermesRuntimeSamplingProfileSerializerTest.cpp
@@ -0,0 +1,234 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <hermes/inspector-modern/chrome/HermesRuntimeSamplingProfileSerializer.h>
+
+#include <hermes/Public/SamplingProfiler.h>
+
+#include <gtest/gtest.h>
+
+#include <deque>
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
+
+namespace facebook::react::jsinspector_modern::tracing {
+
+namespace fhsp = facebook::hermes::sampling_profiler;
+
+using Kind = RuntimeSamplingProfile::SampleCallStackFrame::Kind;
+
+namespace {
+
+fhsp::Profile makeProfile(std::vector<fhsp::ProfileSample> samples) {
+  return fhsp::Profile{
+      std::move(samples), std::make_unique<std::deque<std::string>>()};
+}
+
+fhsp::ProfileSample makeSample(
+    uint64_t timestamp,
+    uint64_t threadId,
+    std::vector<fhsp::ProfileSampleCallStackFrame> callStack) {
+  return fhsp::ProfileSample{timestamp, threadId, std::move(callStack)};
+}
+
+} // namespace
+
+TEST(
+    HermesRuntimeSamplingProfileSerializerTest,
+    serializesJSFunctionFrameAndConvertsLineAndColumnToZeroBased) {
+  std::vector<fhsp::ProfileSampleCallStackFrame> callStack;
+  // Hermes reports 1-based line/column numbers.
+  callStack.emplace_back(
+      fhsp::ProfileSampleCallStackJSFunctionFrame{
+          "myFunction",
+          /* scriptId */ 42,
+          /* scriptUrl */ "app.js",
+          /* lineNumber */ 10,
+          /* columnNumber */ 5});
+
+  std::vector<fhsp::ProfileSample> samples;
+  samples.emplace_back(makeSample(1000, 7, std::move(callStack)));
+
+  auto profile =
+      HermesRuntimeSamplingProfileSerializer::serializeToTracingSamplingProfile(
+          makeProfile(std::move(samples)));
+
+  EXPECT_EQ(profile.runtimeName, "Hermes");
+  ASSERT_EQ(profile.samples.size(), 1);
+
+  const auto& sample = profile.samples[0];
+  EXPECT_EQ(sample.timestamp, 1000u);
+  EXPECT_EQ(sample.threadId, 7u);
+  ASSERT_EQ(sample.callStack.size(), 1);
+
+  const auto& frame = sample.callStack[0];
+  EXPECT_EQ(frame.kind, Kind::JSFunction);
+  EXPECT_EQ(frame.scriptId, 42u);
+  EXPECT_EQ(frame.functionName, std::string_view{"myFunction"});
+  ASSERT_TRUE(frame.scriptURL.has_value());
+  EXPECT_EQ(*frame.scriptURL, std::string_view{"app.js"});
+  // 1-based -> 0-based conversion.
+  ASSERT_TRUE(frame.lineNumber.has_value());
+  EXPECT_EQ(*frame.lineNumber, 9u);
+  ASSERT_TRUE(frame.columnNumber.has_value());
+  EXPECT_EQ(*frame.columnNumber, 4u);
+}
+
+TEST(
+    HermesRuntimeSamplingProfileSerializerTest,
+    serializesJSFunctionFrameWithoutSourceLocationLeavesOptionalsEmpty) {
+  std::vector<fhsp::ProfileSampleCallStackFrame> callStack;
+  callStack.emplace_back(
+      fhsp::ProfileSampleCallStackJSFunctionFrame{
+          "anonymous", /* scriptId */ 3});
+
+  std::vector<fhsp::ProfileSample> samples;
+  samples.emplace_back(makeSample(500, 1, std::move(callStack)));
+
+  auto profile =
+      HermesRuntimeSamplingProfileSerializer::serializeToTracingSamplingProfile(
+          makeProfile(std::move(samples)));
+
+  ASSERT_EQ(profile.samples.size(), 1);
+  ASSERT_EQ(profile.samples[0].callStack.size(), 1);
+
+  const auto& frame = profile.samples[0].callStack[0];
+  EXPECT_EQ(frame.kind, Kind::JSFunction);
+  EXPECT_EQ(frame.scriptId, 3u);
+  EXPECT_EQ(frame.functionName, std::string_view{"anonymous"});
+  EXPECT_FALSE(frame.scriptURL.has_value());
+  EXPECT_FALSE(frame.lineNumber.has_value());
+  EXPECT_FALSE(frame.columnNumber.has_value());
+}
+
+TEST(
+    HermesRuntimeSamplingProfileSerializerTest,
+    serializesNativeAndHostFramesWithFallbackScriptId) {
+  std::vector<fhsp::ProfileSampleCallStackFrame> callStack;
+  callStack.emplace_back(
+      fhsp::ProfileSampleCallStackNativeFunctionFrame{"arrayPrototypeMap"});
+  callStack.emplace_back(
+      fhsp::ProfileSampleCallStackHostFunctionFrame{"nativeLog"});
+
+  std::vector<fhsp::ProfileSample> samples;
+  samples.emplace_back(makeSample(1, 1, std::move(callStack)));
+
+  auto profile =
+      HermesRuntimeSamplingProfileSerializer::serializeToTracingSamplingProfile(
+          makeProfile(std::move(samples)));
+
+  ASSERT_EQ(profile.samples.size(), 1);
+  const auto& frames = profile.samples[0].callStack;
+  ASSERT_EQ(frames.size(), 2);
+
+  EXPECT_EQ(frames[0].kind, Kind::NativeFunction);
+  EXPECT_EQ(frames[0].functionName, std::string_view{"arrayPrototypeMap"});
+  // Native functions are implemented by the VM, no script to reference.
+  EXPECT_EQ(frames[0].scriptId, 0u);
+  EXPECT_FALSE(frames[0].scriptURL.has_value());
+
+  EXPECT_EQ(frames[1].kind, Kind::HostFunction);
+  EXPECT_EQ(frames[1].functionName, std::string_view{"nativeLog"});
+  EXPECT_EQ(frames[1].scriptId, 0u);
+  EXPECT_FALSE(frames[1].scriptURL.has_value());
+}
+
+TEST(
+    HermesRuntimeSamplingProfileSerializerTest,
+    serializesGarbageCollectorSuspendFrame) {
+  std::vector<fhsp::ProfileSampleCallStackFrame> callStack;
+  callStack.emplace_back(
+      fhsp::ProfileSampleCallStackSuspendFrame{
+          fhsp::ProfileSampleCallStackSuspendFrame::SuspendFrameKind::GC});
+
+  std::vector<fhsp::ProfileSample> samples;
+  samples.emplace_back(makeSample(1, 1, std::move(callStack)));
+
+  auto profile =
+      HermesRuntimeSamplingProfileSerializer::serializeToTracingSamplingProfile(
+          makeProfile(std::move(samples)));
+
+  ASSERT_EQ(profile.samples.size(), 1);
+  // GC suspend frames are surfaced (unlike other suspend frames).
+  ASSERT_EQ(profile.samples[0].callStack.size(), 1);
+  EXPECT_EQ(profile.samples[0].callStack[0].kind, Kind::GarbageCollector);
+}
+
+TEST(
+    HermesRuntimeSamplingProfileSerializerTest,
+    filtersOutNonGarbageCollectorSuspendFrames) {
+  std::vector<fhsp::ProfileSampleCallStackFrame> callStack;
+  // Debugger and Multiple suspend frames must be dropped, GC and JS kept.
+  callStack.emplace_back(
+      fhsp::ProfileSampleCallStackSuspendFrame{
+          fhsp::ProfileSampleCallStackSuspendFrame::SuspendFrameKind::
+              Debugger});
+  callStack.emplace_back(
+      fhsp::ProfileSampleCallStackSuspendFrame{
+          fhsp::ProfileSampleCallStackSuspendFrame::SuspendFrameKind::
+              Multiple});
+  callStack.emplace_back(
+      fhsp::ProfileSampleCallStackSuspendFrame{
+          fhsp::ProfileSampleCallStackSuspendFrame::SuspendFrameKind::GC});
+  callStack.emplace_back(
+      fhsp::ProfileSampleCallStackJSFunctionFrame{"keptFn", /* scriptId */ 8});
+
+  std::vector<fhsp::ProfileSample> samples;
+  samples.emplace_back(makeSample(1, 1, std::move(callStack)));
+
+  auto profile =
+      HermesRuntimeSamplingProfileSerializer::serializeToTracingSamplingProfile(
+          makeProfile(std::move(samples)));
+
+  ASSERT_EQ(profile.samples.size(), 1);
+  const auto& frames = profile.samples[0].callStack;
+  ASSERT_EQ(frames.size(), 2);
+  EXPECT_EQ(frames[0].kind, Kind::GarbageCollector);
+  EXPECT_EQ(frames[1].kind, Kind::JSFunction);
+  EXPECT_EQ(frames[1].functionName, std::string_view{"keptFn"});
+}
+
+TEST(
+    HermesRuntimeSamplingProfileSerializerTest,
+    preservesSampleOrderAndPerSampleMetadata) {
+  std::vector<fhsp::ProfileSample> samples;
+  {
+    std::vector<fhsp::ProfileSampleCallStackFrame> callStack;
+    callStack.emplace_back(
+        fhsp::ProfileSampleCallStackJSFunctionFrame{"first", /* scriptId */ 1});
+    samples.emplace_back(makeSample(100, 11, std::move(callStack)));
+  }
+  {
+    std::vector<fhsp::ProfileSampleCallStackFrame> callStack;
+    callStack.emplace_back(
+        fhsp::ProfileSampleCallStackJSFunctionFrame{
+            "second", /* scriptId */ 2});
+    samples.emplace_back(makeSample(200, 22, std::move(callStack)));
+  }
+
+  auto profile =
+      HermesRuntimeSamplingProfileSerializer::serializeToTracingSamplingProfile(
+          makeProfile(std::move(samples)));
+
+  ASSERT_EQ(profile.samples.size(), 2);
+
+  EXPECT_EQ(profile.samples[0].timestamp, 100u);
+  EXPECT_EQ(profile.samples[0].threadId, 11u);
+  ASSERT_EQ(profile.samples[0].callStack.size(), 1);
+  EXPECT_EQ(
+      profile.samples[0].callStack[0].functionName, std::string_view{"first"});
+
+  EXPECT_EQ(profile.samples[1].timestamp, 200u);
+  EXPECT_EQ(profile.samples[1].threadId, 22u);
+  ASSERT_EQ(profile.samples[1].callStack.size(), 1);
+  EXPECT_EQ(
+      profile.samples[1].callStack[0].functionName, std::string_view{"second"});
+}
+
+} // namespace facebook::react::jsinspector_modern::tracing