He played eight years in the National Basketball League (NBL) for the Coburg Giants, the Geelong Cats and the St. Kilda Saints.
After retiring, Breheny coached at NBL level for the Canberra Cannons and the Geelong Supercats.
He also led Women's National Basketball League (WNBL) teams Coburg Cougars and Adelaide Lightning.
[2][3] After retiring from playing, Breheny took on the head coach role at Women's National Basketball League (WNBL) team Coburg Cougars.
In 1993, Breheny resigned as coach of the Supercats after a dispute over his handling of import player Adrian Branch.