diff --git a/esphome/const.py b/esphome/const.py
index f78312a5b0..262f5e0033 100644
--- a/esphome/const.py
+++ b/esphome/const.py
@@ -1102,6 +1102,7 @@ UNIT_MILLIGRAMS_PER_CUBIC_METER = "mg/m³"
 UNIT_MILLIMETER = "mm"
 UNIT_MILLISECOND = "ms"
 UNIT_MILLISIEMENS_PER_CENTIMETER = "mS/cm"
+UNIT_MILLIVOLT = "mV"
 UNIT_MINUTE = "min"
 UNIT_OHM = "Ω"
 UNIT_PARTS_PER_BILLION = "ppb"