diff --git a/homeassistant/components/acaia/config_flow.py b/homeassistant/components/acaia/config_flow.py
index 36727059c8a8a..fb2639fc886df 100644
--- a/homeassistant/components/acaia/config_flow.py
+++ b/homeassistant/components/acaia/config_flow.py
@@ -42,7 +42,7 @@ async def async_step_user(
         errors: dict[str, str] = {}
 
         if user_input is not None:
-            mac = format_mac(user_input[CONF_ADDRESS])
+            mac = user_input[CONF_ADDRESS]
             try:
                 is_new_style_scale = await is_new_scale(mac)
             except AcaiaDeviceNotFound:
@@ -53,12 +53,12 @@ async def async_step_user(
             except AcaiaUnknownDevice:
                 return self.async_abort(reason="unsupported_device")
             else:
-                await self.async_set_unique_id(mac)
+                await self.async_set_unique_id(format_mac(mac))
                 self._abort_if_unique_id_configured()
 
             if not errors:
                 return self.async_create_entry(
-                    title=self._discovered_devices[user_input[CONF_ADDRESS]],
+                    title=self._discovered_devices[mac],
                     data={
                         CONF_ADDRESS: mac,
                         CONF_IS_NEW_STYLE_SCALE: is_new_style_scale,
@@ -99,10 +99,10 @@ async def async_step_bluetooth(
     ) -> ConfigFlowResult:
         """Handle a discovered Bluetooth device."""
 
-        self._discovered[CONF_ADDRESS] = mac = format_mac(discovery_info.address)
+        self._discovered[CONF_ADDRESS] = discovery_info.address
         self._discovered[CONF_NAME] = discovery_info.name
 
-        await self.async_set_unique_id(mac)
+        await self.async_set_unique_id(format_mac(discovery_info.address))
         self._abort_if_unique_id_configured()
 
         try:
diff --git a/homeassistant/components/acaia/entity.py b/homeassistant/components/acaia/entity.py
index 8a2108d26871b..db01b414b9903 100644
--- a/homeassistant/components/acaia/entity.py
+++ b/homeassistant/components/acaia/entity.py
@@ -2,7 +2,7 @@
 
 from dataclasses import dataclass
 
-from homeassistant.helpers.device_registry import DeviceInfo
+from homeassistant.helpers.device_registry import DeviceInfo, format_mac
 from homeassistant.helpers.entity import EntityDescription
 from homeassistant.helpers.update_coordinator import CoordinatorEntity
 
@@ -25,10 +25,11 @@ def __init__(
         super().__init__(coordinator)
         self.entity_description = entity_description
         self._scale = coordinator.scale
-        self._attr_unique_id = f"{self._scale.mac}_{entity_description.key}"
+        formatted_mac = format_mac(self._scale.mac)
+        self._attr_unique_id = f"{formatted_mac}_{entity_description.key}"
 
         self._attr_device_info = DeviceInfo(
-            identifiers={(DOMAIN, self._scale.mac)},
+            identifiers={(DOMAIN, formatted_mac)},
             manufacturer="Acaia",
             model=self._scale.model,
             suggested_area="Kitchen",