Mayweather thanked God and the fans for the victory and added that Berto has heart.
"My career's over. It's official," Mayweather said in the ring. "You've got to know when to hang it up."
Here is a recap of the fight (scoring is unofficial):
Round 1: Mayweather is definitely the aggressor early on with several left jabs. Berto keeps grabbing his trunks with his left hand, not sure if that is a quirk or not. Not much action in the first round as Berto was being very cautious. Not many big punches landed but Mayweather wins the round since he was clearly the more aggressive fighter. Times card: Mayweather 10, Berto 9.
Round 2: Mayweather is able to slip the left jab of Berto early. Lots of grabbing in the middle of the round. Berto is looking a little more lively but hasn't landed much at all. Hardly any action this round, but again, Mayweather lands more punches. Times card: Mayweather 10, Berto 9; Mayweather leads fight, 20-18.
Round 3: Berto finally looks to be pushing the action at the start of the round. Mayweather is consistently evading majority of Berto's shots. Better round for Berto. Times card: Berto 10, Mayweather 9; Mayweather leads fight, 29-28.
Round 4: Berto lands a jab and the crowd responds, but there is still a lot of clinching going on. Mayweather seems intent on punishing Berto's body. Berto is taking some big swings. This round has been the most action packed of the night. Close round for Mayweather. Times card: Mayweather 10, Berto 9; Mayweather leads, 39-37.
Round 5: Lots of clinching in the early minutes of the round and you can hear some boos from the crowd. Mayweather is outboxing Berto right now. Not much action again but Mayweather is starting to dominate. Times card: Mayweather 10, Berto 9; Mayweather leads fight, 49-46.
Round 6: The most action so far with Berto landing a right and Mayweather responding. Lots of clinching in the middle of the ring and the action slows a bit from the start of the round. Mayweather takes another close round. Times card: Mayweather 10, Berto 9; Mayweather leads fight, 59-55.
Round 7: Mayweather lands a good right to the face. Berto just cannot figure Mayweather out, he can't find a way to land many punches at all. The last 20 seconds of the round has had the most action of the fight so far. Both guys landed some punches, but still Mayweather takes the round. Times card: Mayweather 10, Berto 9; Mayweather leads fight, 69-64.
Round 8: Some lefts by Berto to start the round, but Mayweather responds with a stiff left to the face. Mayweather slips away from the ropes and slips a nice right to Berto's chin. Again the last 20 seconds of the round have a bit more action, but this is classic Mayweather right now. Times card: Mayweather 10, Berto 9; Mayweather leads fight, 79-73.
Round 9: Berto throws some wild rights that don't land as Mayweather continues to hammer Berto's body. Some action in the middle of the ring at the 30-second mark but neither fighter lands anything of substance. Mayweather takes it again. Times card: Mayweather 10 Berto 9; Mayweather leads fight, 89-82.
Round 10: Some verbal jabs between the boxers at the start of the round. Referee stops the fight for a bit to tell the boxers to stop talking to each other. A little odd. Mayweather is just way to quick, landing a jab while making Berto miss. Berto is trying to land some combinations in the corner, but Mayweather easily gets off the ropes. Another close one, but this one goes to Berto. Times card: Berto 10, Mayweather 9; Mayweather leads fight, 98-92.
Round 11: Mayweather keeps working the left. He lands a hook in that catches Berto flush. Mayweather yells something to the crowd during the middle of the round. He lands a nice combination at the minute mark and Mayweather looks to be playing to the crowd. The crowd responds with cheers. Loudest ovation of the night. Times card: Mayweather 10, Berto 9; Mayweather leads fight, 108-101.
Round 12: Is this it for Mayweather? We'll see. He seems set to tie Rocky Marciano at 49-0. Will he go for 50? He definitely isn't going to win any new fans tonight as this was a classic Mayweather exhibition. Crowd on their feet at the minute mark as it looked like Mayweather might be trying to finish Berto. Mayweather lifts his hands in the air at the end. Mayweather will win this. Times card: Mayweather 10, Berto 9; Mayweather wins the fight, 118-110.
It's official: Mayweather wins a unanimous decision, with the judges scoring it: 117-111, 118-110 and 120-108.
Here are some undercard results:
Roman Martinez (29-2-3, 17 KO) keeps the WBO junior-lightweight belt with a draw against Orlando Salido (42-13-3, 29 KO).
Badou Jack (20-1-1) defeated George Groves (21-3) and keeps the super-middleweight WBC title with a split decision.
The last of the undercard fights is next with Roman Martinez (29-2-2) facing off against Orlando Salido (42-13-2). After that it'll be the main event.
Jonathan Oquendo (26-4) scored a majority decision over Jhonny Gonzalez (58-10) in the first of the fights on the Mayweather vs. Berto undercard.