Mordington is an agricultural parish in the extreme south-east of Berwickshire in the Scottish Borders region. It is five miles from Berwick-upon-Tweed and borders Northumberland to the east, and south (where the boundary is the Whiteadder Water), Foulden to the west, and Lamberton to the north. The parish is bisected by the A6105 Berwick to Duns road. The lower part of the parish is covered by the Edrington estate.