Educated at Schull National school, he came to the Colony of Queensland in 1887 to join his brother, John Leahy and began work as a journalist with the Brisbane Courier.

He then moved to Western Queensland where he established The Herald newspaper in Thargomindah and became secretary of the Bulloo Divisional Board.

[4] In November 1907, Leahy was appointed as Secretary for Public Works and Mines but at the 1908 state election, he lost the seat to Harry Coyne of the Labour Party.

When the State Governor, Sir Hamilton Goold-Adams was being pressured by the Labour Government to make additional appointments to the council, he called on Leahy who was opposed to the idea to hear his views on the matter.

Leahy was constantly and strenuously opposed to any legislation that savoured of socialist or communist ideals.