diff --git a/Misc/NEWS.d/next/Library/2023-11-08-15-58-57.gh-issue-111804.uAXTOL.rst b/Misc/NEWS.d/next/Library/2023-11-08-15-58-57.gh-issue-111804.uAXTOL.rst
new file mode 100644
index 00000000000000..2696f2f492a8b0
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2023-11-08-15-58-57.gh-issue-111804.uAXTOL.rst
@@ -0,0 +1,2 @@
+Remove posix.fallocate() under WASI as the underlying posix_fallocate() is
+not available in WASI preview2.
diff --git a/Modules/clinic/posixmodule.c.h b/Modules/clinic/posixmodule.c.h
index 9473dd70ff1460..9c54935bafa617 100644
--- a/Modules/clinic/posixmodule.c.h
+++ b/Modules/clinic/posixmodule.c.h
@@ -8558,7 +8558,7 @@ os_truncate(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObject
 
 #endif /* (defined HAVE_TRUNCATE || defined MS_WINDOWS) */
 
-#if (defined(HAVE_POSIX_FALLOCATE) && !defined(POSIX_FADVISE_AIX_BUG))
+#if (defined(HAVE_POSIX_FALLOCATE) && !defined(POSIX_FADVISE_AIX_BUG) && !defined(__wasi__))
 
 PyDoc_STRVAR(os_posix_fallocate__doc__,
 "posix_fallocate($module, fd, offset, length, /)\n"
@@ -8603,7 +8603,7 @@ os_posix_fallocate(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
     return return_value;
 }
 
-#endif /* (defined(HAVE_POSIX_FALLOCATE) && !defined(POSIX_FADVISE_AIX_BUG)) */
+#endif /* (defined(HAVE_POSIX_FALLOCATE) && !defined(POSIX_FADVISE_AIX_BUG) && !defined(__wasi__)) */
 
 #if (defined(HAVE_POSIX_FADVISE) && !defined(POSIX_FADVISE_AIX_BUG))
 
@@ -12403,4 +12403,4 @@ os_waitstatus_to_exitcode(PyObject *module, PyObject *const *args, Py_ssize_t na
 #ifndef OS_WAITSTATUS_TO_EXITCODE_METHODDEF
     #define OS_WAITSTATUS_TO_EXITCODE_METHODDEF
 #endif /* !defined(OS_WAITSTATUS_TO_EXITCODE_METHODDEF) */
-/*[clinic end generated code: output=a05abdc48e3def44 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=0f216bf44ea358f9 input=a9049054013a1b77]*/
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 45debb9845e6c2..73b80e4a0548f3 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -12165,7 +12165,10 @@ os_truncate_impl(PyObject *module, path_t *path, Py_off_t length)
 #endif
 
 
-#if defined(HAVE_POSIX_FALLOCATE) && !defined(POSIX_FADVISE_AIX_BUG)
+/* GH-111804: Due to posix_fallocate() not having consistent semantics across
+   OSs, support was dropped in WASI preview2. */
+#if defined(HAVE_POSIX_FALLOCATE) && !defined(POSIX_FADVISE_AIX_BUG) && \
+    !defined(__wasi__)
 /*[clinic input]
 os.posix_fallocate
 
@@ -12203,7 +12206,7 @@ os_posix_fallocate_impl(PyObject *module, int fd, Py_off_t offset,
     errno = result;
     return posix_error();
 }
-#endif /* HAVE_POSIX_FALLOCATE) && !POSIX_FADVISE_AIX_BUG */
+#endif /* HAVE_POSIX_FALLOCATE) && !POSIX_FADVISE_AIX_BUG && !defined(__wasi__) */
 
 
 #if defined(HAVE_POSIX_FADVISE) && !defined(POSIX_FADVISE_AIX_BUG)