diff --git a/doc/releases/migration-guide-4.0.rst b/doc/releases/migration-guide-4.0.rst
index 740c38e8ca5..9395e39eac9 100644
--- a/doc/releases/migration-guide-4.0.rst
+++ b/doc/releases/migration-guide-4.0.rst
@@ -24,6 +24,9 @@ Kernel
 Boards
 ******
 
+* :ref:`native_posix<native_posix>` has been deprecated in favour of
+  :ref:`native_sim<native_sim>` (:github:`76898`).
+
 Modules
 *******
 
diff --git a/doc/releases/release-notes-4.0.rst b/doc/releases/release-notes-4.0.rst
index 8e24ac17619..b4a8e7a9378 100644
--- a/doc/releases/release-notes-4.0.rst
+++ b/doc/releases/release-notes-4.0.rst
@@ -66,6 +66,9 @@ Boards & SoC Support
 
 * Made these board changes:
 
+  * :ref:`native_posix<native_posix>` has been deprecated in favour of
+    :ref:`native_sim<native_sim>`.
+
 * Added support for the following shields:
 
 Build system and Infrastructure