Mayweather, 38, easily outboxed his younger opponent over the 12 rounds to retain his WBC and WBA welterweight titles and improve his perfect career record to 49-0, matching the benchmark set by former heavyweight champion Rocky Marciano.
Five-division world champion Mayweather dominated most of the exchanges in the MGM Grand Garden Arena with his lightning jabs, control of space and agile movement about the ring to finish well ahead on all three judges’ scorecards.
Berto, a 30-1 underdog against one of the best defensive fighters of all time, dropped to 30-4 as he suffered his fourth loss in his last seven fights.
“Andre Berto has heart, a tremendous chin, he wouldn’t lay down,” Mayweather said in a ringside interview after sinking to his knees after the final bell sounded before looking up at the rafters as the fans snapped pictures with their cell phones.
“It was a good fight. I knew he would be a tough competitor. Experience played a major role tonight. He is a very athletic boxer. What can I say? I was the better man tonight.”
Asked if he might be tempted to come back for a 50th fight, Mayweather replied: “My career is over. It’s official. I’m financially secure and I’m in good health.
“You’ve got to know when it’s time to hang it up, so I think it’s about time for me to hang it up. I’m close to 40 years old, I’ve been in this sport 19 years, been world champion for 18 years, I’ve broken all records.
“There’s nothing left to prove in the sport of boxing,” said Mayweather, who has made more than $700 million during his stellar career.
Back in the ring for the first time since May when he beat Manny Pacquiao in a ‘mega-fight’ that became the richest bout in boxing, Mayweather landed 232 of 410 punches thrown while Berto connected with just 83 of 495.
Mayweather also dominated the jabs count, connecting with 83 of 191 compared to his opponent’s paltry 39 of 301.