 His mother was Elizabeth, daughter of Sir Thomas Harries, 1st Baronet, of Tong Castle, Shropshire.He was the uncle of Robert Pierrepont, 3rd Earl of Kingston-upon-Hull, William Pierrepont, 4th Earl of Kingston-upon-Hull, and Evelyn Pierrepont, 1st Duke of Kingston-upon-Hull.Pierrepont was returned to Parliament as one of two representatives for Appleby in 1698, a seat he held until 1705.