diff --git a/Help/manual/cmake-variables.7.rst b/Help/manual/cmake-variables.7.rst
index 315c73d65f..51458fbdb7 100644
--- a/Help/manual/cmake-variables.7.rst
+++ b/Help/manual/cmake-variables.7.rst
@@ -346,6 +346,7 @@ Variables that Describe the System
    /variable/MSVC_VERSION
    /variable/MSYS
    /variable/UNIX
+   /variable/WASI
    /variable/WIN32
    /variable/WINCE
    /variable/WINDOWS_PHONE
diff --git a/Help/variable/CMAKE_SYSTEM_NAME.rst b/Help/variable/CMAKE_SYSTEM_NAME.rst
index e9ffec47bf..681ee03c58 100644
--- a/Help/variable/CMAKE_SYSTEM_NAME.rst
+++ b/Help/variable/CMAKE_SYSTEM_NAME.rst
@@ -85,6 +85,7 @@ Value                     Name
 ``UNIX_SV``               SCO UnixWare (pre release 7)
 ``UnixWare``              SCO UnixWare 7
 ``visionOS``              Apple mixed reality operating system
+``WASI``                  WebAssembly System Interface
 ``watchOS``               Apple watch operating system
 ``Windows``               Windows stationary operating systems
 ``WindowsCE``             Windows Embedded Compact
diff --git a/Help/variable/WASI.rst b/Help/variable/WASI.rst
new file mode 100644
index 0000000000..eacfc3f9fd
--- /dev/null
+++ b/Help/variable/WASI.rst
@@ -0,0 +1,7 @@
+WASI
+----
+
+.. versionadded:: 3.31
+
+Set to ``1`` when the target system is WebAssembly System Interface
+(:variable:`CMAKE_SYSTEM_NAME` is ``WASI``).
diff --git a/Modules/Platform/WASI-Initialize.cmake b/Modules/Platform/WASI-Initialize.cmake
new file mode 100644
index 0000000000..b49713f1bb
--- /dev/null
+++ b/Modules/Platform/WASI-Initialize.cmake
@@ -0,0 +1 @@
+set(WASI 1)
diff --git a/Modules/Platform/WASI.cmake b/Modules/Platform/WASI.cmake
new file mode 100644
index 0000000000..8e4a05bac7
--- /dev/null
+++ b/Modules/Platform/WASI.cmake
@@ -0,0 +1 @@
+# WASI Platform