Piers was the son of Sir William Piers and Martha, daughter of Sir James Ware and Mary Bryden, and sister of the antiquarian Sir
James Ware. He was the grandson of
Henry Piers and great-grandson of the English naval officer
William Piers, who had been granted Tristernagh Abbey by
Elizabeth I of England as a reward for military and other services in Ireland. Piers served as a military officer in the 1640s, commanding a company in Colonel Castle's Regiment. He held the office of Sheriff of Counties Longford and Westmeath in 1657–1658. He was MP for
St Johnstown, County Longford between 1661 and 1666 and held the office of
High Sheriff of Westmeath in 1663. ==Works==