He was the eldest son of John Mordaunt, 1st Baron Mordaunt of Turvey by Elizabeth, the daughter and coheiress of Sir Henry Vere of Great Addington, Northamptonshire. He was knighted in 1533 and inherited the title Baron Mordaunt on his father's death in 1562.
He died in 1571 and was buried at Turvey. He had married twice: firstly Ella, the daughter and heiress of John Fitzlewis, with whom he had several sons and 6 daughters and secondly Joan, the daughter of Richard Fermor of Easton Neston, Northamptonshire, and the widow of Robert Wilford of London. He was succeeded by his estranged son Lewis.
Stanley T. Bindoff, John S. Roskell, Lewis Namier, Romney Sedgwick, David Hayton, Eveline Cruickshanks, R. G. Thorne, P. W. Hasler, The House of Commons: 1509 - 1558; 1, Appendices, constituencies, members A - C, Volume 4 (1982), p. 614; Google Books