The 2012 Toronto FC season was the sixth season in Toronto FC's existence. The club missed the playoffs for the sixth consecutive season, having never made a post-season appearance. Their season began on March 7 with the quarterfinal of the Champions League against the Los Angeles Galaxy. They ultimately reached the semi-finals of the tournament where they lost to Mexican side Santos Laguna.
Toronto FC started the 2012 Major League Soccer season with a nine-game losing streak; a new league record. Aron Winter was dismissed as head coach and was replaced by Paul Mariner. Winter had only won one away match during his tenure as head coach. Mariner became the 7th coach in franchise history. Prior to Winter dismissal, he agreed to take over the youth academy and Mariner would become head coach. However, the night before the changes were to be announced, he asked to be relieved of all duties. Toronto FC failed to qualify the 2012 MLS Cup Playoffs. Torsten Frings suffered a hip injury late in the season and missed the remainder of the season, ending his Toronto FC career.
On September 27, Toronto FC stated on their Facebook page that, "waiving ticketing fees" for the remaining home games between 10 a.m. on the morning of September 27 and 10 a.m. on September 29. Many season-ticket holders were angry over the discount. Paul Beirne, senior director of business operations, stated "it's the cumulative effect of a really difficult season."
On October 6 against D.C. United, some people in the supporters section wore paper bags over their heads.
Paul Mariner showed interest in Olof Mellberg after watching Sweden vs. England at Euro 2012. The club pursued the player and agreed to a deal worth $3 million over two years was agreed to in principle. However, the league refuse to let the deal happen. The club was furious the league had decided to not let the Bosman transfer to happen. Major League Soccer claims that they went to the MLSE board of directors and try to convince them not to sign Mellberg. MLS commissioner Don Garber stated "Let's put Mellberg aside. The league hasn't nixed that. Toronto has decided it didn't make sense for them." A source that the Toronto Star says that would know of the situation stated that Garber's statement was "absolutely untrue. Not 99 per cent untrue. It's 100 per cent untrue." A rumour circulated within the club that "the league had polled other teams for their thoughts on the deal."