diff --git a/homeassistant/components/mqtt/discovery.py b/homeassistant/components/mqtt/discovery.py
index 23453e146ed..92ad50b7b4a 100644
--- a/homeassistant/components/mqtt/discovery.py
+++ b/homeassistant/components/mqtt/discovery.py
@@ -139,6 +139,14 @@ async def async_start(  # noqa: C901
                 key = DEVICE_ABBREVIATIONS.get(key, key)
                 device[key] = device.pop(abbreviated_key)
 
+        if CONF_AVAILABILITY in payload:
+            for availability_conf in cv.ensure_list(payload[CONF_AVAILABILITY]):
+                if isinstance(availability_conf, dict):
+                    for key in list(availability_conf):
+                        abbreviated_key = key
+                        key = ABBREVIATIONS.get(key, key)
+                        availability_conf[key] = availability_conf.pop(abbreviated_key)
+
         if TOPIC_BASE in payload:
             base = payload.pop(TOPIC_BASE)
             for key, value in payload.items():
diff --git a/tests/components/mqtt/test_discovery.py b/tests/components/mqtt/test_discovery.py
index 50c0a50bd40..77d7093830e 100644
--- a/tests/components/mqtt/test_discovery.py
+++ b/tests/components/mqtt/test_discovery.py
@@ -945,9 +945,9 @@ async def test_discovery_expansion(hass, mqtt_mock_entry_no_yaml_config, caplog)
         '      "payload_not_available": "not_available"'
         "    },"
         "    {"
-        '      "topic":"avail_item2/~",'
-        '      "payload_available": "available",'
-        '      "payload_not_available": "not_available"'
+        '      "t":"avail_item2/~",'
+        '      "pl_avail": "available",'
+        '      "pl_not_avail": "not_available"'
         "    }"
         "  ],"
         '  "dev":{'
@@ -999,9 +999,9 @@ async def test_discovery_expansion_2(hass, mqtt_mock_entry_no_yaml_config, caplo
         '  "stat_t": "test_topic/~",'
         '  "cmd_t": "~/test_topic",'
         '  "availability": {'
-        '    "topic":"~/avail_item1",'
-        '    "payload_available": "available",'
-        '    "payload_not_available": "not_available"'
+        '    "t":"~/avail_item1",'
+        '    "pl_avail": "available",'
+        '    "pl_not_avail": "not_available"'
         "  },"
         '  "dev":{'
         '    "ids":["5706DF"],'