He was the father of Lady Mary.

Born in 1665, he was returned to Parliament for East Retford in 1689, but his stay in the House of Commons was brief, for in the following year the peerage descended to him.

In December, 1706, the higher dignity that had once been in his family was revived in his favour, and he was created Earl of Dorchester, with a special remainder, failing heirs male of his body, to his uncle Gervase Pierrepont, who had himself been raised to the peerage as Lord Pierrepont of Ardglass in Ireland and later was given the dignity of Lord Pierrepont of Hanslope in Buckinghamshire.

Lord Pierrepont died in 1715, and both his titles became extinct.
The Marquess married Mary, daughter of William Feilding, third Earl of Denbigh, by his first wife, Mary, sister of John, first Baron of Kingston, in the peerage of Ireland.

Lady Mary was, therefore, a relation of the novelist, Henry Fielding, whose surname was spelt differently because, he explained, his branch of the family was the only one that could spell correctly.
Of this marriage, there was issue: (i.) William, who took the style of Viscount Newark until 1706, and then was known as Earl of Kingston until his death in 1713, at the age of twenty-one.