Fitz-John was the eldest son of John Fitzgeoffrey and Isabel Bigod.

John married Margery, daughter of Philip Basset and his wife Hawise de Lovaine.

During 1263, FitzJohn joined the baronial revolt led by Simon de Montfort, Earl of Leicester.

He was a leader of a division of the baronial army at the Battle of Lewes.

FitzJohn was forfeited of his lands, with King Henry III of England granting them to Gilbert de Clare, Earl of Gloucester.