Winterstein played all 26 matches for the Cowboys in the recently completed 2012 NRL season after first joining the club from the Brisbane Broncos at the start of 2011.
Cowboys General Manager – Football Peter Parr said Winterstein’s professionalism was one of the key factors that led to his contract extension.
“There’s no doubt that Antonio does everything he can to put himself in a position to perform to the best of his ability each weekend and I think we saw the results of that in 2012,” Parr said.
“Everyone at the club was disappointed that he had the broken jaw, pectoral and shoulder injuries that spoiled his first season with us, but he bounced back like we thought he would and played every game this year.
“He’s still got plenty of good football ahead of him and we’re happy he’s going to be with us for another four seasons.”