Nugent was a native of Pallas in east County Galway, an estate that his great-grandfather, Richard Nugent, 2nd Earl of Westmeath, had acquired in 1621.
His father was Thomas Nugent, 1st Baron Nugent of Riverston, his mother Marianna Barnewall (a daughter of Henry Barnewall, 2nd Viscount Barnewall of Kingsland and Hon.
In 1694 he was outlawed for high treason, probably for supporting James II during the Williamite War in Ireland.
However, he must have been rehabilitated, as he served as a Cornet Charles Mordaunt, 3rd Earl of Peterborough's Dragoons while in Spain.
In February 1737 he recovered his estate by Act of Parliament 1728.