If the welterweight champion ends his career as planned, his legacy will be underpinned by the extraordinary numbers he has brought to the sport, the former heavyweight champion says.
Mayweather has said his title defence against Andre Berto in as Vegas on Saturday night will be his last fight. I he wins, as is widely expected, he will match the record of 49-0 held by former heavyweight great Rocky Marciano.
If it turns out to be his farewell appearance, he will bow out as boxing's richest prize fighter, having set records in annual earnings, pay-per-view buys and gate receipts.
"Mayweather has made more money than anybody else in boxing," says Holyfield, who won the world heavyweight title a record five times.
"He's brought the game up in a way no other fighter has. He took boxing and turned it to a whole other level, whether people believe it or not.
"I don't think we ever thought a welterweight or a middleweight would make more money than a heavyweight but that is what this man has done," Holyfield said on Thursday.
“Money” Mayweather, 38, topped the Forbes list of the world's 100 highest-paid celebrities in June, with an estimated $300 million in earnings over the previous 12 months.
Holyfield, who had a career record of 44-10-2, with one no contest, when he retired in June last year, expressed mixed feelings over Mayweather's legacy as a fighter.
"He is undefeated, which speaks for itself," said the 52-year-old American, who was nicknamed The Real Deal. "He can fight. He's everything that a lot of people may not give him credit for.
"But he has done things his own way, which has been good but has been bad too. When you talk about being the undisputed champion, he has never been an undisputed champion, but he claimed to be it."
Mayweather is widely regarded as one of the best defensive fighters of all time, and prides himself on his ability to evade punishment with his skilful movement and to make adjustments on the fly.
