After three decades as a stand-up comedian, Sweeney was a relative latecomer to the acting profession. He made his television debut alongside Kenneth Branagh, in 1982's Too Late to Talk to Billy. A number of minor roles in acclaimed films such as The Crying Game (1992) and The Butcher Boy (1997) followed. However, it is as irascible farmer Eamonn Byrne, in long-running BBC series Ballykissangel, that Sweeney is most fondly remembered.
Part of Première, a short film production scheme designed to showcase local, Northern Irish film-making talent. It provided a training opportunity for industry new entrants and more experienced crew alike, offering film-makers a global audience and a stepping stone in their careers.