UFC legend Georges St-Pierre announces his retirement from mixed martial arts and says he wanted to leave on his own terms. (0:47)

Georges St-Pierre, arguably the greatest mixed martial artist of all time, officially announced his retirement Thursday at a news conference in Montreal.

St-Pierre, 37, exits the sport as the most dominant UFC welterweight of all time. He defended the 170-pound title a record nine consecutive times from 2008 to 2013 and became a two-weight champion in November 2017 when he submitted Michael Bisping at UFC 217 for the middleweight belt.

He is tied with Bisping for the second-most wins in UFC history (20), behind active lightweight Donald Cerrone (22). Fighting out of Montreal, St-Pierre, who had an overall professional record of 26-2, was one of the UFC's biggest pay-per-view draws.

"There's no tears. I'm very happy to do it," St-Pierre said Thursday. "It takes a lot of discipline to retire on top. It was a long process in my mind, but it's time to do it. Only a few people have done it.

"I always said I wanted to retire on my own and not be told to retire. It takes discipline. In combat sports, that's how you should retire. You should retire on top. That is very hard to do. I'm happy I have the discipline and the wisdom to do it."

St-Pierre confirmed that he recently expressed interest in a fight against undefeated lightweight champion Khabib Nurmagomedov (27-0) to the UFC, but he said the promotion has "other plans" for the Dagestani titleholder.

Nurmagomedov, who is not expected to fight again until November, publicly asked St-Pierre on Wednesday to put off his retirement for one last fight.

"We tried to organize the fight," St-Pierre said. "I know Khabib wanted it and I wanted it, but the UFC has other plans. For me, it's about taking one fight at a time, instead of being there for several fights. The way the business works, I believe, if the UFC promotes someone, they want to keep him there -- to have a guarantee. I don't have that same motivation.

"I knew [Nurmagomedov] wanted to fight me, and his message excited me. Unfortunately, it takes two fighters and also an organization to make that fight happen. The UFC has other plans for Khabib, and I wish him the best of luck."

St-Pierre said he left on "very good terms" with his longtime promoter.

"Georges has cemented his legacy as one of the pound-for-pound greatest fighters ever," UFC president Dana White said in a released statement. "He beat all the top guys during his welterweight title reign and even went up a weight class to win the middleweight championship. He spent years as one of the biggest names in MMA and remains one of the best ambassadors for the sport. He put Canada on the MMA map."

St-Pierre began his professional career in 2002. He debuted with the UFC in 2004 and remained in the organization the rest of his career.

He won his first welterweight championship in November 2006 by knocking out Matt Hughes at UFC 65. He surrendered the belt in his very next fight to Matt Serra in what remains one of the most iconic upsets in UFC history.

That would prove to be the final loss of St-Pierre's career. He reclaimed the title in 2008 and remained champion until 2013, when he willingly vacated the belt to take a break from the sport. He returned to face Bisping in late 2017, after which he vacated the middleweight title as well.

When asked to describe his proudest moment in the sport, St-Pierre said it was surviving a head kick knockdown in a title fight against Carlos Condit in 2012.

"The moment I'm most proud of is when I got dropped with the head kick by Carlos Condit, fell down and was able to stand up," St-Pierre said. "It sounds weird. People think it would be a victory or a knockout, but for me it was when I got dropped by a head kick and survived it."