During a game against the Milwaukee Brewers on April 20, 2014, Martin was involved in a brawl which was started when Carlos Gómez hit a triple off Gerrit Cole after which Martin was suspended 2 games by the MLB on April 22, 2014 for his role in the brawl.
On November 18, 2014, the Toronto Blue Jays announced that they had signed Martin to a five-year, $82 million contract. Early in spring training, manager John Gibbons told reporters that Martin would be R.A. Dickey's catcher during practice and in preseason games, to give him the opportunity to practice catching Dickey's knuckleball. Martin received a standing ovation from the fans at Olympic Stadium on April 3, as the Blue Jays played their final two spring training games in Montreal for the second consecutive year. On April 19, 2015, Martin caught Jeff Francis in his debut for the Blue Jays, and in doing so formed the first all-Canadian battery in franchise history. On June 2, Martin stole home off the back end of a double steal, and became the first Blue Jay to steal home since Brett Lawrie did so in 2012. Martin established a new career-high in home runs on September 26, hitting his 22nd of the season to aid the Blue Jays to a 10–8 win over the Tampa Bay Rays. He ended the 2015 regular season with a .240 batting average, 23 home runs, and 77 RBI in 129 games. He led the major leagues in passed balls, with 19. Martin was announced as a finalist for the catcher Gold Glove award, along with Salvador Pérez and Jason Castro.