The surname originates in the parish of Cairns in mid-Calder, West Lothian.
The first to appear on the records is William de Carnys who witnessed a charter in 1349. Throughout the 14th century this name is recorded on many occasions, and it was particularly common in the mid and west Lothian areas.
William Carnys and his son Duncan received a charter of the baronies of Esterquytburne and Westirquitburne from David II (top) in 1363.
In 1372 William de Carnys was constable of Linlithgow Castle and later, of Edinburgh Castle.
Thomas de Karnys was a cleric and notary public of the diocese of St Andrews and William de Karnis held the same office in 1406.
Alexander de Carnys who witnessed a charter of the lands of Cranshaws in 1401 is likely the same Alexander who was provost of Lincluden in 1408. He was the first de Carnys in Galloway, where he aquired a large amounts of land which were subsequently bestowed on his nephew John, who was the founder of the Galloway branch of the family.
The name is fairly common in Edinburgh from the 16th century onwards.