As a youth, St. Pierre played in the 1997 Quebec International Pee-Wee Hockey Tournament with a minor ice hockey team from Hawkesbury, Ontario. Undrafted, St. Pierre was a graduate of the Guelph Storm of the Ontario Hockey League, where he won the Wayne Gretzky Trophy in 2004. St. Pierre then played his first professional season in 2004–05 with the Greenville Grrrowl of the ECHL and the Edmonton Roadrunners of the AHL. On November 3, 2005, Martin was signed as a free agent by the Chicago Blackhawks and was assigned to the Norfolk Admirals of the AHL. He made his NHL debut with the Blackhawks in the 2005–06 season. St. Pierre spent the majority of the next two seasons in the AHL with the Admirals and the Rockford IceHogs. He also had a brief spell in the Russian Super League prior to the 2007–08 season with Khimik Mytishchi. After appearing in only 21 games with the Blackhawks through parts of 3 seasons, St. Pierre was traded to the Boston Bruins for Pascal Pelletier on July 24, 2008. St. Pierre was then assigned to the Bruins affiliate, the Providence Bruins. On December 20, 2008, Martin received his first call-up to the Bruins. He played his first game for Boston, recording an assist, in a 6-3 win over the St. Louis Blues on December 21, 2008. On December 30, 2008 St. Pierre scored his first Bruins goal, in a 5-2 Bruins road win over the Pittsburgh Penguins as a shorthanded goal. On July 1, 2009, St. Pierre signed a one-year contract with the Ottawa Senators. He was assigned to the Binghamton Senators. He was called up to Ottawa and played his first game for Ottawa against the Florida Panthers on January 9, 2010. On June 6, 2010, St. Pierre left the NHL for Europe signing a one-year contract with Russian team, HC Neftekhimik Nizhnekamsk, of the KHL. On July 11, 2011, St. Pierre signed a one-year contract with the Blue Jackets He was assigned to the Blue Jackets' AHL affiliate, the Springfield Falcons, where he would spend the remainder of the season, playing in 73 games and leading the team in points, recording 11 goals and 53 assists. On July 2, 2012, St. Pierre signed a contract to return with the Blackhawks AHL affiliate, the Rockford IceHogs. On July 6, 2013, St. Pierre signed a one-year two-way deal as a free agent with the Montreal Canadiens. In the 2013-14 season, St. Pierre was originally assigned to the Canadiens AHL affiliate, the Hamilton Bulldogs. He remained with the Bulldogs for the majority of the year, playing in a solitary game with the Canadiens in his one recall to the NHL. On July 24, 2014, St. Pierre returned to Europe, agreeing to a one-year deal with Croatian club, KHL Medveščak Zagreb, of the KHL. He finished the season at Lausanne HC. On August 9, 2015, St. Pierre signed a contract with KHL club Barys Astana of Kazakhstan. He later accepted naturalised citizenship with Kazakhstan and represented the country at the 2017 IIHF Division I World Championships. In his third and final season under contract with Astana in 2017–18, St. Pierre was traded by the club to Russian outfit, Admiral Vladivostok in exchange for James Wright on November 24, 2017. In July 2019, St. Pierre signed with the Sheffield Steelers of the British Elite Ice Hockey League, however he was released by the club just two months later.
