The pair were both awarded James Tait Black Memorial Prizes, joining the ranks of acclaimed writers to receive the honour including DH Lawrence, Evelyn Waugh and Graham Greene.
The prizes are for the best work of fiction and the best biography published during the previous 12 months and are the only major British book awards judged by scholars and students. Man Booker prize winner Byatt was given the fiction prize of 10,000 for her much-praised novel The Children's Book.
Literary critic Carey, a familiar face and voice on arts review shows, was awarded the 10,000 biography prize for his book William Golding: The Man Who Wrote Lord Of The Flies. Golding himself was a James Tait Black prize-winner in 1979.
The winners were announced by crime writer Ian Rankin at the Edinburgh International Book Festival.