 He began his career in 1972 at the Theater der Courage in Vienna.Between 1974–76 he performed at the Viennese Volkstheater, then went on to the Thalia-Theater in Hamburg before returning to Austria in 1978 and joining the Viennese Burgtheater's ensemble, where he soon became a crowd favourite.In 1988, Hackl debuted as theater director at the Volkstheater.