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, 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. It is possibly the warmest parish in Scotland; the annual hours of sunshine are said to be almost as high as at Dunbar, which records the most hours in Scotland.

Berwickshire or the County of Berwick is a historic county, registration county and lieutenancy area in south-eastern Scotland, on the English border. The county takes its name from Berwick-upon-Tweed, its original county town, which was part of Scotland at the time of the county's formation in the twelfth century, but became part of England in 1482 after several centuries of swapping back and forth between the two kingdoms. After the loss of Berwick, Duns and Greenlaw both served as county town at different periods.