He was born at Rathdowney, County Laois, He entered the public school at Kilkenny College in January 1697, and stayed there until April 1699; among his school-fellows was George Berkeley, with whom he formed a lifelong friendship.

[1] With Samuel Madden and eleven other friends, Prior in 1731 established the Dublin Society for the Promotion of Agriculture, Manufactures, Arts, and Sciences, at a meeting of held in Trinity College, 25 June 1731;[1][4] others involved included Francis Bindon, Patrick Delany, and Sir Thomas Molyneux.

[1][6] Prior died on 21 October 1751, and was buried at Rathdowny, A monument was erected by subscription to his memory in Christ Church Cathedral, Dublin, with an inscription in Latin by Berkeley, who styled him "Societatis Dubliniensis auctor, institutor, curator".

[1][7] In 1729, appeared at Dublin Prior's List of the Absentees of Ireland, and in the following year he published Observations on Coin.

To Lord Chesterfield, who had met him as Lord-Lieutenant of Ireland, Prior in 1746 dedicated An Authentic Narrative of the Success of Tar-water in Curing a great number and variety of Distempers.