Career
Born in Killinkere, County Cavan, Ireland, he was ordained to the priesthood in June 1728. He was appointed as Roman Catholic Bishop of Clogher on 11 September 1747 following the appointment of his predecessor, Ross Roe MacMahon as Archbishop of Armagh. Hugh O'Reilly was ordained a bishop on 13 November 1747.
He died in office on 28 March 1778 having served as bishop of his diocese for almost thirty-one years.