diff --git a/homeassistant/components/mqtt/__init__.py b/homeassistant/components/mqtt/__init__.py
index dd51b276715..16f584db011 100644
--- a/homeassistant/components/mqtt/__init__.py
+++ b/homeassistant/components/mqtt/__init__.py
@@ -245,11 +245,11 @@ async def async_check_config_schema(
             for config in config_items:
                 try:
                     schema(config)
-                except vol.Invalid as ex:
+                except vol.Invalid as exc:
                     integration = await async_get_integration(hass, DOMAIN)
                     # pylint: disable-next=protected-access
                     message = conf_util.format_schema_error(
-                        hass, ex, domain, config, integration.documentation
+                        hass, exc, domain, config, integration.documentation
                     )
                     raise ServiceValidationError(
                         message,
@@ -258,7 +258,7 @@ async def async_check_config_schema(
                         translation_placeholders={
                             "domain": domain,
                         },
-                    ) from ex
+                    ) from exc
 
 
 async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
diff --git a/homeassistant/components/mqtt/client.py b/homeassistant/components/mqtt/client.py
index 2e4d49b4cd9..c87d4c9244a 100644
--- a/homeassistant/components/mqtt/client.py
+++ b/homeassistant/components/mqtt/client.py
@@ -124,7 +124,10 @@ async def async_publish(
     """Publish message to a MQTT topic."""
     if not mqtt_config_entry_enabled(hass):
         raise HomeAssistantError(
-            f"Cannot publish to topic '{topic}', MQTT is not enabled"
+            f"Cannot publish to topic '{topic}', MQTT is not enabled",
+            translation_key="mqtt_not_setup_cannot_publish",
+            translation_domain=DOMAIN,
+            translation_placeholders={"topic": topic},
         )
     mqtt_data = get_mqtt_data(hass)
     outgoing_payload = payload
@@ -174,15 +177,21 @@ async def async_subscribe(
     """
     if not mqtt_config_entry_enabled(hass):
         raise HomeAssistantError(
-            f"Cannot subscribe to topic '{topic}', MQTT is not enabled"
+            f"Cannot subscribe to topic '{topic}', MQTT is not enabled",
+            translation_key="mqtt_not_setup_cannot_subscribe",
+            translation_domain=DOMAIN,
+            translation_placeholders={"topic": topic},
         )
     try:
         mqtt_data = get_mqtt_data(hass)
-    except KeyError as ex:
+    except KeyError as exc:
         raise HomeAssistantError(
             f"Cannot subscribe to topic '{topic}', "
-            "make sure MQTT is set up correctly"
-        ) from ex
+            "make sure MQTT is set up correctly",
+            translation_key="mqtt_not_setup_cannot_subscribe",
+            translation_domain=DOMAIN,
+            translation_placeholders={"topic": topic},
+        ) from exc
     async_remove = await mqtt_data.client.async_subscribe(
         topic,
         catch_log_exception(
@@ -606,8 +615,8 @@ class MQTT:
                     del simple_subscriptions[topic]
             else:
                 self._wildcard_subscriptions.remove(subscription)
-        except (KeyError, ValueError) as ex:
-            raise HomeAssistantError("Can't remove subscription twice") from ex
+        except (KeyError, ValueError) as exc:
+            raise HomeAssistantError("Can't remove subscription twice") from exc
 
     @callback
     def _async_queue_subscriptions(
diff --git a/homeassistant/components/mqtt/mixins.py b/homeassistant/components/mqtt/mixins.py
index d84f430bd85..76300afb97a 100644
--- a/homeassistant/components/mqtt/mixins.py
+++ b/homeassistant/components/mqtt/mixins.py
@@ -457,8 +457,8 @@ async def async_setup_entity_entry_helper(
                 if TYPE_CHECKING:
                     assert entity_class is not None
                 entities.append(entity_class(hass, config, entry, None))
-            except vol.Invalid as ex:
-                error = str(ex)
+            except vol.Invalid as exc:
+                error = str(exc)
                 config_file = getattr(yaml_config, "__config_file__", "?")
                 line = getattr(yaml_config, "__line__", "?")
                 issue_id = hex(hash(frozenset(yaml_config)))
diff --git a/homeassistant/components/mqtt/models.py b/homeassistant/components/mqtt/models.py
index 2da2527ad7b..63b8d537170 100644
--- a/homeassistant/components/mqtt/models.py
+++ b/homeassistant/components/mqtt/models.py
@@ -247,15 +247,15 @@ class MqttValueTemplate:
                         payload, variables=values
                     )
                 )
-            except Exception as ex:
+            except Exception as exc:
                 _LOGGER.error(
                     "%s: %s rendering template for entity '%s', template: '%s'",
-                    type(ex).__name__,
-                    ex,
+                    type(exc).__name__,
+                    exc,
                     self._entity.entity_id if self._entity else "n/a",
                     self._value_template.template,
                 )
-                raise ex
+                raise exc
             return rendered_payload
 
         _LOGGER.debug(
diff --git a/homeassistant/components/mqtt/strings.json b/homeassistant/components/mqtt/strings.json
index 7f8dcfedd9a..f35cd7c2b58 100644
--- a/homeassistant/components/mqtt/strings.json
+++ b/homeassistant/components/mqtt/strings.json
@@ -214,7 +214,13 @@
   },
   "exceptions": {
     "invalid_platform_config": {
-      "message": "Reloading YAML config for manually configured MQTT `{domain}` failed. See logs for more details."
+      "message": "Reloading YAML config for manually configured MQTT `{domain}` item failed. See logs for more details."
+    },
+    "mqtt_not_setup_cannot_subscribe": {
+      "message": "Cannot subscribe to topic '{topic}', make sure MQTT is set up correctly."
+    },
+    "mqtt_not_setup_cannot_publish": {
+      "message": "Cannot publish to topic '{topic}', make sure MQTT is set up correctly."
     }
   }
 }