The American business magazine’s data reveals that sport’s highest earners made a staggering $3.2 billion between them over the last 12 months, up 17 percent from the year before — but only two of the top 100 are female.
Nicknamed “Money,” Mayweather has raked in $300 million (£194 million) in the past 12 months, almost double the tally of second-placed Manny Pacquiao, the man he defeated in Las Vegas last month.
Much of Mayweather’s money came from that bout, with the boxer — who leads the Forbes list for the third time in four years — being paid $100m for the fight, with further revenue coming from pay-per-view sales, sponsorship, gate receipts and endorsement deals.
His huge earnings dwarf the previous record set by golfer Tiger Woods, who banked $115m in 2008.
Pacquiao’s $160m haul took him from 11th last year to second this time, with $23m coming from his fight with Chris Algieri in Macau, China, late last year.
Spanish football’s great rivals Cristiano Ronaldo and Lionel Messi are third and fourth respectively, with Real Madrid’s Portuguese star having made $79.6m.
Messi, who led Barcelona to a trophy treble of the La Liga title, Spanish Cup and Champions League, is on the same salary as Ronaldo, and Forbes estimates that $22m of his total $73.8m earnings came from off-pitch deals.
Tennis legend Roger Federer, who made $67m — $58m of it from sponsorship deals with firms including Nike and Rolex — is the fifth highest-paid.
Basketball stars LeBron James ($64.8m) and Kevin Durant ($54.1m) occupy sixth and seventh places, with golf’s Phil Mickelson ($50.8m) and Woods ($50.6m) in eighth and ninth.
A 14-time major champion, Woods has endured a wretched run of form on the golf course and this month carded the worst round of his professional career at the prestigious Memorial Tournament in Ohio.
Of his total earnings, only $600,000 came from golf, with the remaining $50m from endorsements. His dramatic loss of form and struggle with injuries have seen him make only seven cuts in the 13 events he played in during 2014 and the first half of 2015.
Injuries also restricted the number of lucrative appearances he could make in overseas events, affecting his standing on the rich list.
Basketball’s Kobe Bryant is in 10th, with his $64.8m haul including $23.5m in salary and winnings.
The top 100 includes athletes from 10 sports, including 27 from the world of baseball.
Its only two female representatives are both tennis players.
Maria Sharapova is the highest placed, with her $29.7m putting her in 26th, while French Open champion Serena Williams earned $24.6m over the 12 months and stands in 47th place.
The Forbes figures include all salaries, prize money and bonuses paid out between June 1 last year and the same date this year.
The magazine says its calculations are “based on conversations with dozens of industry insiders” and adds: “We do not deduct for taxes or agents’ fees and we do not include investment income.”