Munro played his first NHL game on March 1, 2004 against the Nashville Predators, earning a 2-2 tie for the Blackhawks. In the 2003-04 season, Munro played in seven games for the Blackhawks, earning a 1-5-1 record with a 3.67 goals against average and an .880 save percentage. Munro was in competition with fellow Blackhawks goaltender Michael Leighton for the backup goaltender position on the team. Munro also played 12 games for the Blackhawks' AHL affiliate, the Norfolk Admirals, winning 5 games.
Munro did not return to the NHL until the 2005-06 season, where he played 10 games for the Blackhawks, compiling a 3-5-2 record with a 3.00 GAA and .893 save percentage. He also recorded his first career shutout on January 26, 2006 against the Calgary Flames, as the Blackhawks recorded the 2-0 victory.
Munro was signed as a free agent by HC Fribourg-Gotteron in Switzerland on July 7, 2006. Munro played in 41 games for Fribourg-Gotteron during the 2006-07 season, compiling a 12-28 record. He spent the 2007-08 season with the Columbus Blue Jackets' AHL affiliate, the Syracuse Crunch. Playing in 25 games for the Crunch, Munro went 13-9-1 with a respectable 2.42 GAA and a .913 save percentage. Munro also recorded 2 shutouts on the year for the Crunch.
Munro signed with the Toronto Marlies prior to the start of the 2008-09 season, where he was intended to become the backup goaltender to Toronto Maple Leafs prospect Justin Pogge.