diff --git a/changelog.d/17945.misc b/changelog.d/17945.misc
new file mode 100644
index 00000000000..eeebb921699
--- /dev/null
+++ b/changelog.d/17945.misc
@@ -0,0 +1 @@
+Enable encrypted appservice related experimental features in the complement docker image.
diff --git a/docker/complement/conf/workers-shared-extra.yaml.j2 b/docker/complement/conf/workers-shared-extra.yaml.j2
index b9334cc53bb..9a74c617bc4 100644
--- a/docker/complement/conf/workers-shared-extra.yaml.j2
+++ b/docker/complement/conf/workers-shared-extra.yaml.j2
@@ -104,6 +104,16 @@ experimental_features:
   msc3967_enabled: true
   # Expose a room summary for public rooms
   msc3266_enabled: true
+  # Send to-device messages to application services
+  msc2409_to_device_messages_enabled: true
+  # Allow application services to masquerade devices
+  msc3202_device_masquerading: true
+  # Sending device list changes, one-time key counts and fallback key usage to application services
+  msc3202_transaction_extensions: true
+  # Proxy OTK claim requests to exclusive ASes
+  msc3983_appservice_otk_claims: true
+  # Proxy key queries to exclusive ASes
+  msc3984_appservice_key_query: true
 
 server_notices:
   system_mxid_localpart: _server