Floyd Joy Mayweather Jr. (né Sinclair; born February 24, 1977) is an American boxing promoter and former professional boxer who competed between 1996 and 2017. He retired with an undefeated record and won 15 major world championships spanning five weight classes from super featherweight to light middleweight. This includes the Ring magazine title in three weight classes. As an amateur, he won a bronze medal in the featherweight division at the 1996 Olympics, three U.S. Golden Gloves championships (at light flyweight, flyweight, and featherweight), and the U.S. national championship at featherweight. After retiring from professional boxing in August 2017, he transitioned to exhibition boxing.

As of July 2025, BoxRec ranks him the third greatest boxer of all time, pound for pound. Mayweather was named "Fighter of the Decade" for the 2010s by the Boxing Writers Association of America (BWAA) and The Sporting News, a two-time winner of The Ring magazine's Fighter of the Year award (1998 and 2007), a three-time winner of the BWAA Fighter of the Year award (2007, 2013, and 2015), and a six-time winner of the Best Fighter ESPY Award (2007–2010, 2012–2014). In 2016, ESPN ranked him the greatest boxer, pound for pound, of the last 25 years; in 2024, they also ranked him the best boxer of the 21st century.

He is referred to as one of the best defensive boxers in history: since the existence of CompuBox, Mayweather is the most accurate puncher among professional boxers, having the highest plus–minus ratio in recorded boxing history. He has a tied record with Joe Louis of 26 consecutive wins in world title fights. He also holds 24 wins (7 KOs) against former or current world titlists, and 8 wins (3 KOs) against International Boxing Hall of Fame inductees. He was inducted into the International Boxing Hall of Fame in the class of 2021.

Mayweather is one of the most lucrative pay-per-view attractions of all time, in any sport. He topped the Forbes and Sports Illustrated lists of the 50 highest-paid athletes of 2012 and 2013, and the Forbes list again in both 2014 and 2015, as the highest-paid athlete in the world. In 2006, he founded his own boxing promotional firm, Mayweather Promotions, after leaving Bob Arum's Top Rank. He has generated approximately 24 million PPV buys and $1.67 billion in revenue throughout his career. In 2018, he was the highest-paid athlete in the world, with total earnings, including endorsements, of $285 million, according to Forbes. In November, 2021, Sportico released an all-time athlete earnings list, in which Mayweather ranked no. 6 all time, totaling an inflation-adjusted $1.2 billion in his career.

Mayweather was born Floyd Joy Sinclair on February 24, 1977, in Grand Rapids, Michigan, into a family of boxers. His father, Floyd Mayweather Sr., is a former welterweight contender who fought Hall of Famer Sugar Ray Leonard. His uncles Jeff and the late Roger Mayweather were professional boxers, with the latter—Floyd's former trainer—winning two world championships, as well as fighting Hall of Famers Julio César Chávez, Pernell Whitaker, and Kostya Tszyu. Mayweather was born with his mother's last name, but his last name would change to Mayweather shortly thereafter. His maternal grandfather was born in Kingston, Jamaica. He attended Ottawa Hills High School before dropping out.

Boxing has been a part of Mayweather's life since his childhood and he never seriously considered any other profession. "I think my grandmother saw my potential first," he said. "When I was young, I told her, 'I think I should get a job.' She said, 'No, just keep boxing.'" During the 1980s, Mayweather lived in the Hiram Square neighborhood of New Brunswick, New Jersey, where his mother had relatives. He later said, "When I was about eight or nine, I lived in New Jersey with my mother and we were seven deep in one bedroom and sometimes we didn't have electricity. When people see what I have now, they have no idea of where I came from and how I didn't have anything growing up."

It was common for the young Mayweather to come home from school and find used heroin needles in his front yard. His mother was addicted to drugs, and he had an aunt who died from AIDS because of her drug use. "People don't know the hell I've been through," he says. The most time that his father spent with him was taking him to the gym to train and work on his boxing, according to Mayweather. "I don't remember him ever taking me anywhere or doing anything that a father would do with a son, going to the park or to the movies or to get ice cream," he says. "I always thought that he liked his daughter [Floyd's older sister] better than he liked me because she never got whippings and I got whippings all the time."

Mayweather's father contends that Floyd is not telling the truth about their early relationship. "Even though his daddy did sell drugs, I didn't deprive my son," the elder Mayweather says. "The drugs I sold, he was a part of it. He had plenty of food. He had the best clothes and I gave him money. He didn't want for anything. Anybody in Grand Rapids can tell you that I took care of my kids". Floyd Sr. says he did all of his hustling at night and spent his days with his son, taking him to the gym and training him to be a boxer. "If it wasn't for me he wouldn't be where he is today," he maintains.