Jo was born in St Andrews, Fife and after education at Eton College, and Balliol College, Oxford, he became a barrister.
In 1938 he married Laura Bonham-Carter.
Upon his retirement he was granted a life peerage, as Baron Grimond, of Firth, Orkney. His Memoirs were published in 1979 by Heinemann of London. Grimond was also the author of a number of books on politics.