diff --git a/changelog.d/6058.docker b/changelog.d/6058.docker
new file mode 100644
index 0000000000000000000000000000000000000000..30be6933c981dc0c7875d03fc7f1d692cdad5edc
--- /dev/null
+++ b/changelog.d/6058.docker
@@ -0,0 +1 @@
+Provide SYNAPSE_WORKER envvar to specify python module.
diff --git a/docker/README.md b/docker/README.md
index d5879c2f2cdb54f59fcf5efd4f0c4a4fc52b5ebc..4b712f3f5cf2bffe6f941efb3ea8713ce4d353c4 100644
--- a/docker/README.md
+++ b/docker/README.md
@@ -89,6 +89,8 @@ The following environment variables are supported in run mode:
   `/data`.
 * `SYNAPSE_CONFIG_PATH`: path to the config file. Defaults to
   `<SYNAPSE_CONFIG_DIR>/homeserver.yaml`.
+* `SYNAPSE_WORKER`: module to execute, used when running synapse with workers.
+   Defaults to `synapse.app.homeserver`, which is suitable for non-worker mode.
 * `UID`, `GID`: the user and group id to run Synapse as. Defaults to `991`, `991`.
 * `TZ`: the [timezone](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones) the container will run with. Defaults to `UTC`.
 
diff --git a/docker/start.py b/docker/start.py
index 260f2d9943ed2fc62af1d5a30aa7d584d287b204..e41ea20e700f0e0a04d5795955bc979f74de8b0e 100755
--- a/docker/start.py
+++ b/docker/start.py
@@ -182,6 +182,7 @@ def main(args, environ):
     mode = args[1] if len(args) > 1 else None
     desired_uid = int(environ.get("UID", "991"))
     desired_gid = int(environ.get("GID", "991"))
+    synapse_worker = environ.get("SYNAPSE_WORKER", "synapse.app.homeserver")
     if (desired_uid == os.getuid()) and (desired_gid == os.getgid()):
         ownership = None
     else:
@@ -245,7 +246,7 @@ def main(args, environ):
 
     log("Starting synapse with config file " + config_path)
 
-    args = ["python", "-m", "synapse.app.homeserver", "--config-path", config_path]
+    args = ["python", "-m", synapse_worker, "--config-path", config_path]
     if ownership is not None:
         args = ["su-exec", ownership] + args
         os.execv("/sbin/su-exec", args)