He played for Penrith Panthers between 1993 and 1995, Sydney Roosters from 1996 to 2001 and for the North Queensland Cowboys between 2002 and 2006. During his career, Sing scored 159 tries, the fifth most in Australian first grade rugby league.
Sing is one of the most prolific try scorers in recent years of the National Rugby League, and has represented Queensland and Australia regularly since 1995.
In 2000, Matt Sing was awarded the Australian Sports Medal for his contribution to Australia's international standing in the sport of rugby league. That year he also played in the Roosters' Grand Final loss to Brisbane.
Sing moved to the North Queensland Cowboys in 2002 and was named the club's player of the year that season.
In 2003 Sing passed the milestone of 100 career tries. In the third game of the 2003 State of Origin series Sing was named man-of-the-match and became one of only a handful of players to score three tries in a State of Origin game. He was the leading try-scorer in the history of the North Queensland Cowboys, having scored 60 tries since joining the club until being overtaken by Matt Bowen.
At the end of the 2003 NRL season, he went on the 2003 Kangaroo tour.
Sing played in the 2005 Grand Final, his second, scoring a try for the Cowboys in their loss to the Tigers.
2006 was Sing's last season in the NRL and he moved to Hull in 2007 to replace the outgoing Nathan Blacklock. He retired at the end of the 2008 season.