Located in the south of what is now County Galway, Aidhne was coextensive with the present diocese of Kilmacduagh. It was bounded on the west by Loch Lurgain (Galway Bay) and the district of Burren in County Clare. County Clare also bounds Aidhne on its south and south-east side. Aidhne is bounded on the east by the low mountains of Slieve Aughty, which separated Uí Fhiachrach Aidhne from Uí Maine.