The list is dominated by athletes from America's NFL, NBA and Major League Baseball competitions, although the top five athletes - Mayweather, Messi, Cristiano Ronaldo, Conor McGregor and Neymar - are from either football or combat sports.
Forbes's sporting rich list is created after calculating an athlete's earnings from prize money, salaries and bonuses in the year to 1 June 2018.
And by the way, in case you're wondering, to make the Forbes 100 cut, it was necessary to earn $22.9M, which is the amount generated by the last man on the list, Charlotte Hornets basketball player Nicolas Batum.
The 41-year-old Mayweather, who last took to the ring in 2017 against Irishman Conor McGregor, reclaimed the top spot from Real Madrid star Cristiano Ronaldo on the annual Forbes list.
It will come as no surprise that being talented at a sport is a good way to become a multi-millionaire, as Forbes' list of the world's 100 highest-paid athletes proves.
NBA's top earner LeBron James banked $85.5 million, including endorsements, over the last 12 months to rank sixth among the highest-paid athletes.
Football icon Cristiano Ronaldo ($108 million) who was the world's highest paid athlete the past two years, has dropped two positions to Number 3.
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11 different sports are coveredin the list, with a record 40 NBA basketball players included in the top 100. Tennis player Serena Williams was the sole female representative past year, coming in at 51st. He ranks second overall with $111 million, including $27 million through endorsement deals with Adidas, Gatorade, Pepsi and Huawei.
Brazil and Paris St Germain star Neymar joins Messi and Ronaldo in the top five.
Kohli is the only cricketer to feature in the top 100. The top 100 earned United States dollars 3.8 billion, a 23 per cent jump over a year ago.
In the top 100 list the National Football League had 18 athletes, 14 were baseball players and nine were footballers.
Others on the list are tennis star Roger Federer (7), golfer Tiger Woods (16), tennis player Rafael Nadal (20) and golfer Rory McIlroy (26).
Golden State Warriors star Stephen Curry was the only other National Basketball Association player to feature in the top 10, with earnings of $101 million.
Forbes said it was harder than ever to qualify for the 100 highest-paid athletes, with the cutoff up Dollars 1.5 million to USD 22.9 million.