Background
O'Neill was the son of Charles O'Neill, Member of Parliament for Randalstown, by Catherine Brodick, daughter of St John Brodrick, of Midleton, County Cork.
Member of Parliament in the Parliament of Ireland
O'Neill was the son of Charles O'Neill, Member of Parliament for Randalstown, by Catherine Brodick, daughter of St John Brodrick, of Midleton, County Cork.
He was returned to the Irish House of Commons for Randalstown in 1760, a seat he held until 1783, and then represented County Antrim between 1783 and 1793. He was sworn of the Irish Privy Council in 1781 and raised to the Peerage of Ireland as Baron O'Neill, of Shane's Castle in the County of Antrim, in 1793. In 1795 he was further honoured when he was made Viscount O'Neill, of Shane's Castle in the County of Antrim, in the Irish peerage.
Lord O'Neill married the Honourable Henrietta Boyle, daughter of Charles Boyle, Viscount Dungarvan, in 1777.