Carnegie was only five when he succeeded his father, who died in harness as Foxite Member for Forfarshire, to the baronetcy and the Kinnaird estate, near Brechin. The elder of two sons born after the consecutive births of ten girls, he was raised by his mother, a cousin of the 1st Lord Minto, and his guardian, the Foxite Whig William Maule*, his father’s successor as county Member. Like his father, he was sent to Eton. He travelled extensively in Europe from 1819. In September 1822 he and Maule accompanied Joseph Hume, radical Member for Aberdeen Burghs, to the ceremony in Arbroath at which he was presented with a piece of plate in recognition of his parliamentary exertions.
In October 1829 Carnegie notified Hume that he intended to stand for Aberdeen Burghs (of which Brechin and Montrose were two, and which his father had represented, 1784-90) at the next election. He undertook a personal canvass, paying particular attention to Brechin council.
Carnegie left public life and devoted himself to his estates. He revived the Southesk peerage claim, but without success. He died at Kinnaird in January 1849. Administration of his personal estate was granted on 21 Apr. 1849 to his eldest son and successor James Carnegie (1827-1905), who in 1855 was raised to the peerage as 6th earl of Southesk after the reversal of the 1716 attainder of his distant kinsman the 5th earl.
