[9] MacKinnon chose to leave his hometown and attend the Minnesota boarding school because of the strength of its ice hockey program.

[8] During the season, MacKinnon was named to the team that represented Nova Scotia in the ice hockey tournament at the 2011 Canada Winter Games.

[16] Because MacKinnon did not speak French, there was speculation that he would follow through with his option to play in the USHL until he was eligible for the NCAA, unless his rights were traded to a different QMJHL team.

He was also named Most Valuable Player, scoring a tournament-best seven goals and six assists in four games, and earned a spot on the Tournament All-Star team.

[24] On June 26, Avalanche Director of Amateur Scouting Richard Pracey said during a conference call that the team had MacKinnon in their sights.

[25] On June 30, the Avalanche did indeed use their first overall pick in the draft to select MacKinnon (while Seth Jones was chosen fourth overall by the Nashville Predators.

[28] MacKinnon scored his first NHL goal October 12, against Michal Neuvirth of the Washington Capitals during the second period at the Verizon Center.

[32] MacKinnon would see his individual production drop having recorded 14 goals and 24 assists for 38 points in 64 games for his sophomore NHL season and the Avalanche would struggle as a team having not qualifying for the playoffs.

[36] Prior to the 2017–18 season, MacKinnon hired a sports psychologist, which drastically helped him improve his play and emerge as one of the league's premier players.

[39] MacKinnon was named the NHL's First Star of the Week for February 26–March 4, 2018, after scoring five goals, six assists, with four power play points, a +6 rating, and 31 shots in four games.

On April 26, MacKinnon was named a finalist for the Ted Lindsay Award as the NHL's most outstanding player for the first time in his career which was eventually won by Edmonton Oilers forward captain Connor McDavid.

[41] The following day he was named a Hart Memorial Trophy finalist for the first time in his career as the NHL's most valuable player in the regular season; the award was eventually won by New Jersey Devils' forward Taylor Hall as MacKinnon finished second in the voting, only 70 votes behind Hall as the award recipient.

On September 11, MacKinnon won the Lady Byng Memorial Trophy, which is awarded to the "player adjudged to have exhibited the best type of sportsmanship and gentlemanly conduct combined with a high standard of playing ability.

This record would be surpassed in August 2023 when Toronto Maple Leafs forward Auston Matthews signed a deal with an AAV of $13.25 million.

[54] On June 27, MacKinnon was declared the winner of the Ted Lindsay Award by the NHL Players' Association, beating out fellow finalists Nikita Kucherov of the Tampa Bay Lightning and Auston Matthews of the Toronto Maple Leafs, respectively.

[55] Additionally, he was also the recipient for the Hart Memorial Trophy as the regular season's most valuable player, beating out the other two finalists of Nikita Kucherov and Connor McDavid, respectively.

[61] The following year, MacKinnon was named to the Canada Atlantic team for the 2012 World U-17 Hockey Challenge in Windsor, Ontario.

[62] On December 13, 2012, MacKinnon was named a member of Team Canada for the 2013 World Junior Ice Hockey Championships along with Mooseheads teammate Jonathan Drouin.

[63] At the 2015 World Championships, where Canada won the gold medal for the first time since 2007 with a perfect 10-0 record, MacKinnon finished the tournament with 4 goals and 5 assists.

[66] Bold indicates led league MacKinnon has appeared in a recurring role (along with former Halifax Mooseheads teammate Cameron Critchlow) on the Canadian television show Mr. D, playing a fictionalized version of himself.

[75] In 2019, he returned in a voice acting role in Trailer Park Boys: The Animated Series season 1 episode 3, again portraying himself.

He, along with fellow Nova Scotian and NHL player Sidney Crosby, have appeared in a series of Tim Hortons commercials produced for YouTube.