Mundine was selected to play for New South Wales in each of the three matches of the 1999 State of Origin series, scoring a try in Game I on debut. That year he also assisted the Dragons' run to the Grand Final, with a hat-trick against the Sharks in the major semi-final. The following week the Dragons lost to the Melbourne Storm in the 1999 NRL Grand Final during which and Mundine, playing at five-eighth knocked-on over the try line early in the second half, which proved to be a major turning point in the match.