Gilbert was the son of Thomas, 1st Earl of Coventry, and his first wife Winifred, daughter of Pierce Edgecumbe, of Mount Edgecumbe. On the death of his nephew Thomas, 3rd Earl, aged 9 at Eton, he succeeded as 4th Earl in 1711-12. He married firstly on 30 November 1694 Dorothy, daughter of Sir William Keyt, 2nd Bt., of Ebrington; they had one daughter Anne. Dorothy died in 1705 and Gilbert married secondly on 25 June 1715, Anne, daughter of Sir Streynsham Master, of Codnor Castle; they had no children. The Earl died on 27 October 1719, and the Barony became extinct; the family estates were inherited by the descendants of the brother of the 1st Lord Coventry.