The grandson of Richard Nugent, 1st Earl of Westmeath, Nugent's father, Christopher, Lord Delvin, had predeceased the first Earl, meaning that Richard Nugent succeeded to the earldom on his grandfather's death in 1641.
While attempting to make his way back to Ireland in December 1641 upon the outbreak of the 1641 Rebellion, Nugent was arrested on suspecion of complicty in the rising.