The origin of this name appears to be territorial, from the lands of that name in the parish of Portmoak in Kinross-shire. Black states that the family was settled there from the middle of the twelfth century and the lands were in the possession of Michael de Arnoth in 1284. According to Nisbet, the family of Arnott of that Ilk held lands in Fife, and Michael De Arnoth was sent as one of two knights escorting Duncan, Earl of Fife, as ambassador to England in 1340. David Arnott, Archdeacon of Lothian in 1502, later became Bishop of Galloway. Sir Michael Arnott of that Ilk was created a baronet by Charles I on 27 July 1629. His successors favoured military careers and held high rank for the next five generations.
This line became extinct when the sixth baronet died without heirs. The other principal families are listed as Arnott of Woodmiln, Balkaithlie, Balcormo and Eastrynd. Hugo Arnott, who succeeded to the Balcormo estates through his mother and assumed the name ‘Arnott of Balcormo’, was a well-known lawyer, antiquarian and historian who, in 1785, published a work on celebrated criminal trials in Scotland. His appearance as a principal character in Kay’s Edinburgh Portraits, demonstrates his renown as a character in that city.