William was the second son of Henry, Baron Norreys of Rycote, and his wife, Margery the daughter of John, Lord Williams. He was with Walter Devereux, Earl of Essex, in Ulster in 1574 and was, on one occasion, rescued from death by his brother, John. He was, it appears, temporarily appointed in 1576, Marshal of Berwick in succession to Sir William Drury, but soon returned to Ireland. He died of a violent fever at Newry on 25th December 1579, and is said to have accurately foretold his own death. Queen Elizabeth sent his mother a letter of condolence. He married Elizabeth, daughter of Sir Richard Morrison, by whom he left a son Francis, later the Earl of Berkshire.