diff --git a/docs/docs/configuration/index.md b/docs/docs/configuration/index.md
index 0489da3aa..0c46c4028 100644
--- a/docs/docs/configuration/index.md
+++ b/docs/docs/configuration/index.md
@@ -52,6 +52,8 @@ mqtt:
   # NOTE: must be unique if you are running multiple instances
   client_id: frigate
   # Optional: user
+  # NOTE: MQTT user can be specified with an environment variables that must begin with 'FRIGATE_'.
+  #       e.g. user: '{FRIGATE_MQTT_USER}'
   user: mqtt_user
   # Optional: password
   # NOTE: MQTT password can be specified with an environment variables that must begin with 'FRIGATE_'.
diff --git a/frigate/config.py b/frigate/config.py
index 6e6c120be..7c4e945aa 100644
--- a/frigate/config.py
+++ b/frigate/config.py
@@ -863,8 +863,9 @@ class FrigateConfig(FrigateBaseModel):
         """Merge camera config with globals."""
         config = self.copy(deep=True)
 
-        # MQTT password substitution
-        if config.mqtt.password:
+        # MQTT user/password substitutions
+        if config.mqtt.user or config.mqtt.password:
+            config.mqtt.user = config.mqtt.user.format(**FRIGATE_ENV_VARS)
             config.mqtt.password = config.mqtt.password.format(**FRIGATE_ENV_VARS)
 
         # Global config to propagate down to camera level