Mayweather won a unanimous decision at the MGM Grand Garden, taking the back-and-forth bout by scores of 117-111, 118-110 and 117-111. Yahoo! Sports had it 115-113 for Mayweather.
The Y! Sports pound-for-pound king smiled as he congratulated Cotto and said, "You are a hell of a champion. You're the toughest guy I ever fought."
"When fights are on pay-per-view, you want to give the fans what they paid for and that's excitement," Mayweather said. "It comes with the territory when you fight a future Hall of Famer like Miguel Cotto. I had to fight hard, suck it up. He's a tough competitor. I knew I'd have to come in the ring, fight hard and execute the game plan.
"Cotto is a future Hall of Famer. He's no pushover, and he came to fight. He didn't come just to survive, he came to fight. I dug down and fought him back."
Before any more talk about a potential superfight against Pacquiao is mulled, Mayweather must serve 87 days beginning June 1 after pleading guilty to domestic violence charges resulting from a 2010 incident involving his girlfriend.
Some thought the impending jail sentence might be a distraction, but he was typically brilliant against Cotto. Mayweather, who was led to the ring by pop singer Justin Bieber, had a 179-105 edge in punches landed, according to CompuBox. More significantly, Mayweather landed the harder shots and seemed to have Cotto in trouble in several rounds.
In particular, Mayweather hurt Cotto in the 12th, wobbling him with a sharp left hand. Cotto kept trying to pressure and work the body, but Mayweather was very good defensively and blocked a lot of Cotto's blows with his arms while they were on the inside.
Cotto, who was pummeled in bouts in 2008 by Antonio Margarito and in 2009 by Pacquiao, made it a competitive fight and brought the crowd to its feet several times by landing hard shots. The problem, though, was that Cotto rarely could land a strong combination.
Much of Mayweather's best work came when Cotto pinned him in the corner. That seemed to be where Cotto wanted the fight, but Mayweather did a terrific job of fighting his way off the ropes, using his fast hands and incredibly accurate punching.
Cotto landed 105 of 506 shots, most of which were thrown with bad intentions. Still, Mayweather showed his mettle by taking whatever Cotto had to give.
Mayweather now has to let his wounds heal – he was bleeding from the nose and face, beginning in the middle of the fight – before he packs up and goes off to jail.
"It comes with the territory," Mayweather said of his upcoming jail term. "In life, there are obstacles, and I take the good with the good and the bad with the bad."