Smith graduated from Westminster School in 2006[2] and played four seasons at Boston College, helping the Eagles win two national championships. While playing for BC, Smith was drafted by the Chicago Blackhawks 169th overall in the sixth round of the 2008 NHL Entry Draft.[citation needed]
On Sunday, April 24, 2011, during Game 6 of the Western Conference quarterfinals, Smith scored the overtime goal on a rebound against the Vancouver Canucks' goaltender, Roberto Luongo, to force a Game 7 in Vancouver after the Canucks had previously been leading the series 3–0. The Blackhawks ended up losing Game 7 in overtime.[4]
On June 17, 2013, Smith was called up to play his first Stanley Cup Finals game, a 2–0 loss to the Boston Bruins, to fill in over the injured Marián Hossa.[5] The Blackhawks won the Cup on June 24, 2013, when they defeated the Bruins in Game 6. On June 27, 2014, the Blackhawks signed him to a two-year contract extension.[6] In the following season, Smith scored four goals in 19 playoff games to help the Blackhawks advance to the Western Conference finals.[5]
On March 2, 2015, Smith was traded by the Blackhawks to the San Jose Sharks in exchange for Andrew Desjardins.[7] He scored his first goal with the Sharks the same day in their shutout game against the Montreal Canadiens,[8] but remained for most of the season with the Sharks' AHL affiliate San Jose Barracuda.[5]
Despite putting up acceptable numbers with the Maple Leafs, Smith was placed on waivers by the team on March 30, 2016. Smith cleared the following day and was assigned to the Toronto Marlies of the AHL.[10] Despite being considered to be favourites to win the Calder Cup, the Marlies were eliminated in the third round of the playoffs, with Smith contributing nine points in their fifteen-game run.[citation needed]
On August 16, 2016, he signed a one-year, two-way deal with the Colorado Avalanche,[11] worth $675,000 at the NHL level and $150,000 at the AHL level.[12] Having made the Avalanche opening night roster, Smith made his debut with Colorado to start the 2016–17 season in a 6–5 victory over the Dallas Stars on October 15, 2016.[13] Smith would play in four scoreless games for the Avalanche before being placed on waivers and being claimed by the Toronto Maple Leafs on October 24, 2016. Smith was claimed due to the depth he provided the team on the penalty kill, a position coach Mike Babcock praised him for during his stint the previous season in Toronto.[14]
In the 2017–18 season, he won the Calder Cup with the Toronto Marlies, serving as team captain.[15] On June 15, 2018, he signed with Adler Mannheim of the German DEL.[16]
After a second stint with Adler Mannheim, Smith remained in the DEL, agreeing to a one-year contract with EHC München on May 10, 2021.[17]