As a youth, Matheson played in the 2006 and 2007 Quebec International Pee-Wee Hockey Tournaments with a minor ice hockey team from West Island. He began his junior career in the Quebec Midget AAA league playing with the Lac St. Louis Lions from 2009 to 2011. Matheson then left to join the Dubuque Fighting Saints of the United States Hockey League, where he led all defenceman in scoring in 2011–12. He then committed to play for Boston College of the NCAA starting in 2012–13. He cited his motivation for leaving his native Quebec was the ability to develop better as a player in the USHL and in the NCAA. Following his freshman year at Boston College, Matheson was named to Hockey East's All-Rookie Team. For his sophomore campaign, Matheson earned All-First Team honours in the Hockey East conference as well as All-Second Team East Honors in the NCAA as determined by the AHCA. Matheson decided on April 30 to remain at Boston College for the 2014–15 season amid rumours of him leaving school to sign with the NHL team that drafted him, the Florida Panthers. On May 8, he was named team captain for the 2014–15 season. At the conclusion of the 2014–15 season, Matheson signed an entry-level contract with the Panthers, forgoing his senior year of NCAA eligibility, and was sent to play with the Panthers' American Hockey League affiliate, the San Antonio Rampage. Matheson made his NHL debut on March 23, 2016, in a 3–1 win over the Winnipeg Jets. He recorded his first career NHL goal the following season on October 18, 2016, against the Tampa Bay Lightning. On October 7, 2017, the Panthers signed Matheson to an eight-year, $39 million contract extension worth $4.875 million annually. On October 13, 2018, during a game against Vancouver Canucks, Matheson hit Canucks forward Elias Pettersson, resulting in Pettersson leaving the game with a concussion. While Matheson was not penalized for the play on the ice, the NHL Department of Player Safety believed that Matheson had an intent to injure, resulting in him being suspended two games and fined $52,419.36. Following the incident, Matheson said, "I know deep down there was no frustration in me when that play happened and there was no intent to injure on my part;" he apologized to Pettersson via text.
Personal life
Matheson met his wife Emily Pfalzer, an American professional hockey player, while playing at Boston College. The two became engaged in the summer of 2018 and married on July 20, 2019.
