diff --git a/UNITTESTS/stubs/CMakeLists.txt b/UNITTESTS/stubs/CMakeLists.txt
index 69195ef31ec..50cfb307ade 100644
--- a/UNITTESTS/stubs/CMakeLists.txt
+++ b/UNITTESTS/stubs/CMakeLists.txt
@@ -9,7 +9,6 @@ add_library(mbed-headers-connectivity INTERFACE)
 add_library(mbed-headers-storage INTERFACE)
 add_library(mbed-headers-hal INTERFACE)
 add_library(mbed-headers-events INTERFACE)
-add_library(mbed-headers-rtos INTERFACE)
 
 target_link_libraries(mbed-headers
     INTERFACE
@@ -101,12 +100,6 @@ target_include_directories(mbed-headers-hal
         ${mbed-os_SOURCE_DIR}/hal/include
 )
 
-target_include_directories(mbed-headers-rtos
-    INTERFACE
-        ${mbed-os_SOURCE_DIR}/rtos/include
-        ${mbed-os_SOURCE_DIR}/rtos/include/rtos
-)
-
 target_include_directories(mbed-headers
     INTERFACE
         ${mbed-os_SOURCE_DIR}/features
@@ -123,7 +116,6 @@ add_subdirectory(connectivity)
 add_subdirectory(events)
 add_subdirectory(hal)
 add_subdirectory(platform)
-add_subdirectory(rtos)
 add_subdirectory(storage)
 
 add_library(mbed-stubs INTERFACE)
diff --git a/UNITTESTS/stubs/connectivity/CMakeLists.txt b/UNITTESTS/stubs/connectivity/CMakeLists.txt
index faba2e38e2d..fdea4287fe1 100644
--- a/UNITTESTS/stubs/connectivity/CMakeLists.txt
+++ b/UNITTESTS/stubs/connectivity/CMakeLists.txt
@@ -57,7 +57,9 @@ target_sources(mbed-stubs-connectivity
 
 target_link_libraries(mbed-stubs-connectivity
     PRIVATE
+        mbed-stubs-rtos-headers
         mbed-headers
         mbed-stubs-headers
+        mbed-stubs-rtos
         gtest
 )
diff --git a/UNITTESTS/stubs/rtos/CMakeLists.txt b/UNITTESTS/stubs/rtos/CMakeLists.txt
deleted file mode 100644
index fc9a759b8d6..00000000000
--- a/UNITTESTS/stubs/rtos/CMakeLists.txt
+++ /dev/null
@@ -1,22 +0,0 @@
-# Copyright (c) 2021 ARM Limited. All rights reserved.
-# SPDX-License-Identifier: Apache-2.0
-
-add_library(mbed-stubs-rtos)
-
-target_sources(mbed-stubs-rtos
-    PRIVATE
-        ConditionVariable_stub.cpp
-        Kernel_stub.cpp
-        mbed_rtos_rtx_stub.c
-        Mutex_stub.cpp
-        rtx_mutex_stub.c
-        Semaphore_stub.cpp
-        ThisThread_stub.cpp
-        Thread_stub.cpp
-)
-
-target_link_libraries(mbed-stubs-rtos
-    PRIVATE
-        mbed-headers
-        mbed-stubs-headers
-)
diff --git a/connectivity/cellular/tests/UNITTESTS/framework/AT/at_cellularcontext/CMakeLists.txt b/connectivity/cellular/tests/UNITTESTS/framework/AT/at_cellularcontext/CMakeLists.txt
index 5772d7cf458..18d9dfc5d9e 100644
--- a/connectivity/cellular/tests/UNITTESTS/framework/AT/at_cellularcontext/CMakeLists.txt
+++ b/connectivity/cellular/tests/UNITTESTS/framework/AT/at_cellularcontext/CMakeLists.txt
@@ -25,6 +25,7 @@ target_link_libraries(${TEST_NAME}
         mbed-headers
         mbed-stubs
         mbed-stubs-headers
+        mbed-stubs-rtos-headers
         gmock_main
 )
 
diff --git a/connectivity/cellular/tests/UNITTESTS/framework/AT/at_cellulardevice/CMakeLists.txt b/connectivity/cellular/tests/UNITTESTS/framework/AT/at_cellulardevice/CMakeLists.txt
index bdf0e684142..8886bc8d56d 100644
--- a/connectivity/cellular/tests/UNITTESTS/framework/AT/at_cellulardevice/CMakeLists.txt
+++ b/connectivity/cellular/tests/UNITTESTS/framework/AT/at_cellulardevice/CMakeLists.txt
@@ -31,6 +31,7 @@ target_link_libraries(${TEST_NAME}
         mbed-headers
         mbed-stubs
         mbed-stubs-headers
+        mbed-stubs-rtos
         gmock_main
 )
 
diff --git a/connectivity/cellular/tests/UNITTESTS/framework/AT/at_cellularstack/CMakeLists.txt b/connectivity/cellular/tests/UNITTESTS/framework/AT/at_cellularstack/CMakeLists.txt
index ca26a782c4c..0bd65fe5e3a 100644
--- a/connectivity/cellular/tests/UNITTESTS/framework/AT/at_cellularstack/CMakeLists.txt
+++ b/connectivity/cellular/tests/UNITTESTS/framework/AT/at_cellularstack/CMakeLists.txt
@@ -29,6 +29,7 @@ target_link_libraries(${TEST_NAME}
         mbed-headers
         mbed-stubs
         mbed-stubs-headers
+        mbed-stubs-rtos-headers
         gmock_main
 )
 
diff --git a/connectivity/cellular/tests/UNITTESTS/framework/device/cellularstatemachine/CMakeLists.txt b/connectivity/cellular/tests/UNITTESTS/framework/device/cellularstatemachine/CMakeLists.txt
index 21953781848..4f056639884 100644
--- a/connectivity/cellular/tests/UNITTESTS/framework/device/cellularstatemachine/CMakeLists.txt
+++ b/connectivity/cellular/tests/UNITTESTS/framework/device/cellularstatemachine/CMakeLists.txt
@@ -30,6 +30,7 @@ target_link_libraries(${TEST_NAME}
         mbed-headers
         mbed-stubs
         mbed-stubs-headers
+        mbed-stubs-rtos-headers
         gmock_main
 )
 
diff --git a/rtos/CMakeLists.txt b/rtos/CMakeLists.txt
index 9e2194d12d3..ab9d3082ea9 100644
--- a/rtos/CMakeLists.txt
+++ b/rtos/CMakeLists.txt
@@ -1,6 +1,10 @@
 # Copyright (c) 2020 ARM Limited. All rights reserved.
 # SPDX-License-Identifier: Apache-2.0
 
+if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME AND BUILD_TESTING)
+    add_subdirectory(tests/UNITTESTS)
+endif()
+
 target_include_directories(mbed-core
     INTERFACE
         .
diff --git a/rtos/tests/.mbedignore b/rtos/tests/.mbedignore
new file mode 100644
index 00000000000..e28badb677d
--- /dev/null
+++ b/rtos/tests/.mbedignore
@@ -0,0 +1 @@
+UNITTESTS/*
diff --git a/rtos/tests/UNITTESTS/CMakeLists.txt b/rtos/tests/UNITTESTS/CMakeLists.txt
new file mode 100644
index 00000000000..b632a73f477
--- /dev/null
+++ b/rtos/tests/UNITTESTS/CMakeLists.txt
@@ -0,0 +1,4 @@
+# Copyright (c) 2021 ARM Limited. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+add_subdirectory(doubles)
diff --git a/rtos/tests/UNITTESTS/doubles/CMakeLists.txt b/rtos/tests/UNITTESTS/doubles/CMakeLists.txt
new file mode 100644
index 00000000000..4216a6ab6c9
--- /dev/null
+++ b/rtos/tests/UNITTESTS/doubles/CMakeLists.txt
@@ -0,0 +1,42 @@
+# Copyright (c) 2021 ARM Limited. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+add_library(mbed-headers-rtos INTERFACE)
+
+target_include_directories(mbed-headers-rtos
+    INTERFACE
+        ${mbed-os_SOURCE_DIR}/rtos/include
+        ${mbed-os_SOURCE_DIR}/rtos/include/rtos
+)
+
+add_library(mbed-stubs-rtos-headers INTERFACE)
+
+target_include_directories(mbed-stubs-rtos-headers
+    INTERFACE
+        .
+)
+
+add_library(mbed-stubs-rtos)
+
+add_definitions(-DUNITTEST)
+
+target_sources(mbed-stubs-rtos
+    PRIVATE
+        ConditionVariable_stub.cpp
+        Kernel_stub.cpp
+        mbed_rtos_rtx_stub.c
+        Mutex_stub.cpp
+        rtx_mutex_stub.c
+        Semaphore_stub.cpp
+        ThisThread_stub.cpp
+        Thread_stub.cpp
+)
+
+target_link_libraries(mbed-stubs-rtos
+    PRIVATE        
+        mbed-headers-base
+        mbed-headers-rtos
+        mbed-headers-platform
+        mbed-headers-drivers
+        mbed-headers-hal
+)
diff --git a/UNITTESTS/stubs/rtos/ConditionVariable_stub.cpp b/rtos/tests/UNITTESTS/doubles/ConditionVariable_stub.cpp
similarity index 100%
rename from UNITTESTS/stubs/rtos/ConditionVariable_stub.cpp
rename to rtos/tests/UNITTESTS/doubles/ConditionVariable_stub.cpp
diff --git a/UNITTESTS/stubs/ConditionVariable_stub.h b/rtos/tests/UNITTESTS/doubles/ConditionVariable_stub.h
similarity index 100%
rename from UNITTESTS/stubs/ConditionVariable_stub.h
rename to rtos/tests/UNITTESTS/doubles/ConditionVariable_stub.h
diff --git a/UNITTESTS/stubs/rtos/Kernel_stub.cpp b/rtos/tests/UNITTESTS/doubles/Kernel_stub.cpp
similarity index 100%
rename from UNITTESTS/stubs/rtos/Kernel_stub.cpp
rename to rtos/tests/UNITTESTS/doubles/Kernel_stub.cpp
diff --git a/UNITTESTS/stubs/rtos/Mutex_stub.cpp b/rtos/tests/UNITTESTS/doubles/Mutex_stub.cpp
similarity index 100%
rename from UNITTESTS/stubs/rtos/Mutex_stub.cpp
rename to rtos/tests/UNITTESTS/doubles/Mutex_stub.cpp
diff --git a/UNITTESTS/stubs/rtos/Semaphore_stub.cpp b/rtos/tests/UNITTESTS/doubles/Semaphore_stub.cpp
similarity index 100%
rename from UNITTESTS/stubs/rtos/Semaphore_stub.cpp
rename to rtos/tests/UNITTESTS/doubles/Semaphore_stub.cpp
diff --git a/UNITTESTS/stubs/Semaphore_stub.h b/rtos/tests/UNITTESTS/doubles/Semaphore_stub.h
similarity index 100%
rename from UNITTESTS/stubs/Semaphore_stub.h
rename to rtos/tests/UNITTESTS/doubles/Semaphore_stub.h
diff --git a/UNITTESTS/stubs/rtos/ThisThread_stub.cpp b/rtos/tests/UNITTESTS/doubles/ThisThread_stub.cpp
similarity index 100%
rename from UNITTESTS/stubs/rtos/ThisThread_stub.cpp
rename to rtos/tests/UNITTESTS/doubles/ThisThread_stub.cpp
diff --git a/UNITTESTS/stubs/rtos/Thread_stub.cpp b/rtos/tests/UNITTESTS/doubles/Thread_stub.cpp
similarity index 100%
rename from UNITTESTS/stubs/rtos/Thread_stub.cpp
rename to rtos/tests/UNITTESTS/doubles/Thread_stub.cpp
diff --git a/UNITTESTS/stubs/Thread_stub.h b/rtos/tests/UNITTESTS/doubles/Thread_stub.h
similarity index 100%
rename from UNITTESTS/stubs/Thread_stub.h
rename to rtos/tests/UNITTESTS/doubles/Thread_stub.h
diff --git a/UNITTESTS/stubs/rtos/mbed_rtos_rtx_stub.c b/rtos/tests/UNITTESTS/doubles/mbed_rtos_rtx_stub.c
similarity index 100%
rename from UNITTESTS/stubs/rtos/mbed_rtos_rtx_stub.c
rename to rtos/tests/UNITTESTS/doubles/mbed_rtos_rtx_stub.c
diff --git a/UNITTESTS/stubs/rtos/rtx_mutex_stub.c b/rtos/tests/UNITTESTS/doubles/rtx_mutex_stub.c
similarity index 100%
rename from UNITTESTS/stubs/rtos/rtx_mutex_stub.c
rename to rtos/tests/UNITTESTS/doubles/rtx_mutex_stub.c