 He was also a Justice of the Peace for County Antrim, and Deputy Lieutenant for County Londonderry, and was High Sheriff of County Londonderry in 1871.O'Neill stood for parliament unsuccessfully at Antrim in 1885 and was elected as Member of Parliament for Antrim Mid later in the year in the 1885 general election.He held this seat until his death in 1910, and was succeeded as MP by his nephew Arthur O'Neill.