 He was the son of was John O'Byrne of Corville, County Tipperary (who had originally been granted the title of Count by the Pope) and his mother was Eleanor von Hübner, the daughter of Austrian diplomat Count Joseph Alexander Hübner.He was a direct descendant of Edward Byrne (c.1739–1804), a wealthy Dublin merchant and Chairman of the Catholic Convention which campaigned for Catholic rights, and his son John Dominick Byrne, who was a member of the United Irishmen.Patrick O'Byrne married Bernadette Boland in Sneem, County Kerry in 1897.