diff --git a/src/tests/kits/support/Jamfile b/src/tests/kits/support/Jamfile
index 68dba47c87..9522c878c3 100644
--- a/src/tests/kits/support/Jamfile
+++ b/src/tests/kits/support/Jamfile
@@ -9,6 +9,7 @@ SEARCH_SOURCE += [ FDirName $(SUBDIR) blocker ] ;
 SEARCH_SOURCE += [ FDirName $(SUBDIR) bmemoryio ] ;
 SEARCH_SOURCE += [ FDirName $(SUBDIR) bstring ] ;
 SEARCH_SOURCE += [ FDirName $(SUBDIR) bblockcache ] ;
+SEARCH_SOURCE += [ FDirName $(SUBDIR) bstopwatch ] ;
 
 UnitTestLib libsupporttest.so
 	: SupportKitTestAddon.cpp
@@ -80,6 +81,9 @@ UnitTestLib libsupporttest.so
 		BlockCacheExerciseTest.cpp
 		BlockCacheConcurrencyTest.cpp
 
+		# BStopWatch
+		BStopWatchTest.cpp
+
 	: be [ TargetLibstdc++ ] libsupporttest_RemoteTestObject.so
 ;
 
@@ -91,4 +95,3 @@ SimpleTest string_utf8_tests : string_utf8_tests.cpp : be ;
 SubInclude HAIKU_TOP src tests kits support barchivable ;
 #SubInclude HAIKU_TOP src tests kits support bautolock ;
 #SubInclude HAIKU_TOP src tests kits support blocker ;
-
diff --git a/src/tests/kits/support/SupportKitTestAddon.cpp b/src/tests/kits/support/SupportKitTestAddon.cpp
index 5f614a08fa..a00e329321 100644
--- a/src/tests/kits/support/SupportKitTestAddon.cpp
+++ b/src/tests/kits/support/SupportKitTestAddon.cpp
@@ -9,6 +9,7 @@
 #include "bmemoryio/MallocIOTest.h"
 #include "bstring/StringTest.h"
 #include "bblockcache/BlockCacheTest.h"
+#include "bstopwatch/BStopWatchTest.h"
 #include "ByteOrderTest.h"
 #include "DateTimeTest.h"
 
@@ -27,7 +28,9 @@ getTestSuite()
 	suite->addTest("BMallocIO", MallocIOTestSuite());
 	suite->addTest("BString", StringTestSuite());
 	suite->addTest("BBlockCache", BlockCacheTestSuite());
+	suite->addTest("BStopWatch", BStopWatchTestSuite());
 	suite->addTest("ByteOrder", ByteOrderTestSuite());
 
 	return suite;
 }
+
diff --git a/src/tests/kits/support/bstopwatch/BStopWatchTest.cpp b/src/tests/kits/support/bstopwatch/BStopWatchTest.cpp
new file mode 100644
index 0000000000..154df062c7
--- /dev/null
+++ b/src/tests/kits/support/bstopwatch/BStopWatchTest.cpp
@@ -0,0 +1,207 @@
+/*
+ * Copyright 2026, Haiku, Inc. All Rights Reserved.
+ * Distributed under the terms of the MIT License.
+ */
+
+
+#include "BStopWatchTest.h"
+
+#include <cstring>
+#include <unistd.h>
+
+#include <StopWatch.h>
+
+#include <cppunit/TestCaller.h>
+#include <cppunit/TestSuite.h>
+
+
+class BStopWatchTest : public BTestCase {
+public:
+	BStopWatchTest(std::string name = "");
+
+	void NameWithNull_ReturnsEmptyString();
+	void NameWithValidString_ReturnsSetName();
+	void ElapsedTimeAfterDelay_Increases();
+	void ElapsedTimeWhenSuspended_DoesNotChange();
+	void LapWhenRunning_ReturnsIncreasingTime();
+	void LapWhenExceedsMax_StillReturnsValidTime();
+	void LapWhenSuspended_ReturnsZero();
+	void ResetAfterRunning_ClearsElapsedTime();
+	void ElapsedTimeAfterMultipleSuspendResume_OnlyCountsActivePeriods();
+};
+
+
+BStopWatchTest::BStopWatchTest(std::string name)
+	:BTestCase(name)
+{
+}
+
+
+void
+BStopWatchTest::NameWithNull_ReturnsEmptyString()
+{
+	BStopWatch sw(NULL, true);
+
+	const char* name = sw.Name();
+
+	CPPUNIT_ASSERT(strcmp(name, "") == 0);
+}
+
+
+void
+BStopWatchTest::NameWithValidString_ReturnsSetName()
+{
+	BStopWatch sw("mywatch", true);
+
+	const char* name = sw.Name();
+
+	CPPUNIT_ASSERT(strcmp(name, "mywatch") == 0);
+}
+
+
+void
+BStopWatchTest::ElapsedTimeAfterDelay_Increases()
+{
+	BStopWatch sw("et", true);
+	bigtime_t t1 = sw.ElapsedTime();
+	CPPUNIT_ASSERT(t1 >= 0);
+
+	usleep(10000);
+
+	bigtime_t t2 = sw.ElapsedTime();
+	CPPUNIT_ASSERT(t2 > 0);
+	CPPUNIT_ASSERT(t2 > t1);
+}
+
+
+void
+BStopWatchTest::ElapsedTimeWhenSuspended_DoesNotChange()
+{
+	BStopWatch sw("sr", true);
+	usleep(5000);
+
+	sw.Suspend();
+	bigtime_t t1 = sw.ElapsedTime();
+	usleep(10000);
+	bigtime_t t2 = sw.ElapsedTime();
+
+	CPPUNIT_ASSERT_EQUAL(t1, t2);
+
+	sw.Resume();
+	usleep(5000);
+	bigtime_t t3 = sw.ElapsedTime();
+
+	CPPUNIT_ASSERT(t3 > t2);
+}
+
+
+void
+BStopWatchTest::LapWhenRunning_ReturnsIncreasingTime()
+{
+	BStopWatch sw("lap", true);
+
+	usleep(2000);
+	bigtime_t l1 = sw.Lap();
+	usleep(2000);
+	bigtime_t l2 = sw.Lap();
+
+	CPPUNIT_ASSERT(l2 > l1);
+}
+
+
+void
+BStopWatchTest::LapWhenExceedsMax_StillReturnsValidTime()
+{
+	BStopWatch sw("lapoverflow", true);
+
+	for (int i = 0; i < 12; i++)
+		sw.Lap();
+
+	CPPUNIT_ASSERT(sw.Lap() > 0);
+}
+
+
+void
+BStopWatchTest::LapWhenSuspended_ReturnsZero()
+{
+	BStopWatch sw("lap2", true);
+	sw.Suspend();
+
+	bigtime_t lapTime = sw.Lap();
+
+	CPPUNIT_ASSERT_EQUAL((bigtime_t)0, lapTime);
+}
+
+
+void
+BStopWatchTest::ResetAfterRunning_ClearsElapsedTime()
+{
+	BStopWatch sw("reset", true);
+	usleep(50000);
+	sw.Lap();
+	bigtime_t beforeReset = sw.ElapsedTime();
+	CPPUNIT_ASSERT(beforeReset >= 50000);
+
+	sw.Reset();
+
+	CPPUNIT_ASSERT(sw.ElapsedTime() < 5000);
+}
+
+
+void
+BStopWatchTest::ElapsedTimeAfterMultipleSuspendResume_OnlyCountsActivePeriods()
+{
+	BStopWatch sw("multi", true);
+
+	usleep(2000);
+	sw.Suspend();
+	usleep(2000);
+	sw.Resume();
+	usleep(2000);
+	sw.Suspend();
+	usleep(2000);
+	sw.Resume();
+	usleep(2000);
+	sw.Suspend();
+
+	bigtime_t elapsed = sw.ElapsedTime();
+	CPPUNIT_ASSERT(elapsed >= 6000);
+	CPPUNIT_ASSERT(elapsed < 7000);
+}
+
+
+CppUnit::Test*
+BStopWatchTestSuite()
+{
+	CppUnit::TestSuite* suite = new CppUnit::TestSuite("BStopWatch");
+
+	suite->addTest(new CppUnit::TestCaller<BStopWatchTest>(
+		"BStopWatchTest::NameWithNull_ReturnsEmptyString",
+		&BStopWatchTest::NameWithNull_ReturnsEmptyString));
+	suite->addTest(new CppUnit::TestCaller<BStopWatchTest>(
+		"BStopWatchTest::NameWithValidString_ReturnsSetName",
+		&BStopWatchTest::NameWithValidString_ReturnsSetName));
+	suite->addTest(new CppUnit::TestCaller<BStopWatchTest>(
+		"BStopWatchTest::ElapsedTimeAfterDelay_Increases",
+		&BStopWatchTest::ElapsedTimeAfterDelay_Increases));
+	suite->addTest(new CppUnit::TestCaller<BStopWatchTest>(
+		"BStopWatchTest::ElapsedTimeWhenSuspended_DoesNotChange",
+		&BStopWatchTest::ElapsedTimeWhenSuspended_DoesNotChange));
+	suite->addTest(new CppUnit::TestCaller<BStopWatchTest>(
+		"BStopWatchTest::LapWhenRunning_ReturnsIncreasingTime",
+		&BStopWatchTest::LapWhenRunning_ReturnsIncreasingTime));
+	suite->addTest(new CppUnit::TestCaller<BStopWatchTest>(
+		"BStopWatchTest::LapWhenExceedsMax_StillReturnsValidTime",
+		&BStopWatchTest::LapWhenExceedsMax_StillReturnsValidTime));
+	suite->addTest(new CppUnit::TestCaller<BStopWatchTest>(
+		"BStopWatchTest::LapWhenSuspended_ReturnsZero",
+		&BStopWatchTest::LapWhenSuspended_ReturnsZero));
+	suite->addTest(new CppUnit::TestCaller<BStopWatchTest>(
+		"BStopWatchTest::ResetAfterRunning_ClearsElapsedTime",
+		&BStopWatchTest::ResetAfterRunning_ClearsElapsedTime));
+	suite->addTest(new CppUnit::TestCaller<BStopWatchTest>(
+		"BStopWatchTest::ElapsedTimeAfterMultipleSuspendResume_OnlyCountsActivePeriods",
+		&BStopWatchTest::ElapsedTimeAfterMultipleSuspendResume_OnlyCountsActivePeriods));
+
+	return suite;
+}
diff --git a/src/tests/kits/support/bstopwatch/BStopWatchTest.h b/src/tests/kits/support/bstopwatch/BStopWatchTest.h
new file mode 100644
index 0000000000..856f512965
--- /dev/null
+++ b/src/tests/kits/support/bstopwatch/BStopWatchTest.h
@@ -0,0 +1,15 @@
+/*
+ * Copyright 2026, Haiku, Inc. All Rights Reserved.
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef _B_STOPWATCH_TEST_H_
+#define _B_STOPWATCH_TEST_H_
+
+
+#include "TestCase.h"
+
+
+CppUnit::Test* BStopWatchTestSuite();
+
+
+#endif	// _B_STOPWATCH_TEST_H_