diff --git a/changelog.d/12571.feature b/changelog.d/12571.feature
new file mode 100644
index 0000000000..6be907da21
--- /dev/null
+++ b/changelog.d/12571.feature
@@ -0,0 +1 @@
+Add the Synapse function `types.map_username_to_mxid_localpart` to the Module API.