diff --git a/changelog.d/19642.feature b/changelog.d/19642.feature
new file mode 100644
index 0000000000..dfb8e5f5a3
--- /dev/null
+++ b/changelog.d/19642.feature
@@ -0,0 +1 @@
+Advertise [MSC4445](https://github.com/matrix-org/matrix-spec-proposals/pull/4445) sync timeline order in `unstable_features`.
diff --git a/synapse/rest/client/versions.py b/synapse/rest/client/versions.py
index 7bf4b12e8b..bb1711f2cf 100644
--- a/synapse/rest/client/versions.py
+++ b/synapse/rest/client/versions.py
@@ -206,6 +206,8 @@ class VersionsRestServlet(RestServlet):
                     "org.matrix.msc4354": self.config.experimental.msc4354_enabled,
                     # MSC4380: Invite blocking
                     "org.matrix.msc4380.stable": True,
+                    # MSC4445: Sync timeline order
+                    "org.matrix.msc4445.initial_sync_timeline_topological_ordering": True,
                 },
             },
         )