Mayweather, 37, beat Cristiano Ronaldo to top spot with basketball star LeBron James in third.
Mayweather also topped the list in 2013, ousting Tiger Woods who been No 1 for the previous decade.
Woods dropped to No. 6 after topping the list in 2013. According to Forbes, that had plenty to do with the fact that the partnership between Woods and EA Sports ended. Additionally, injuries have kept Woods off the course for part of the year and prevented him from collecting prize money.
‘I'm humbled and extremely fortunate to be recognized by Forbes as the highest-paid athlete once again,’ said Mayweather.
‘I'm doing something that no other athlete is doing, promoting myself and seeing my hard work pay off in the form of record-breaking numbers. It's all about hard work and dedication which is so important and a key part of my financial success.
‘I’m grateful for my family, team and fans. Being able to take care of my family is my number one priority and the level of success that I've achieved allows me to give them the best. I look forward to stepping into the ring in September and doing what I do best.’
The September Mayweather-Canelo fight billed as “The One” set records for highest PPV gross ($150 million), live gate ($20 million) and total revenue (roughly $200 million). The Canelo fight marked the second bout in the blockbuster 30-month, six-fight deal Mayweather signed with Showtime in 2013. Mayweather earned a guaranteed $32 million for his May fight with Marcos Maidana where the PPV buys are expected to finish between 900,000 and one million when they are all counted, compared to 2.2 million for Mayweather-Alvarez. Mayweather is the most popular boxer on the planet which helps drive PPV sales, but his paychecks get a boost because he also serves as fight promoter, in addition to pugilist.
It remains to be seen how much longer Mayweather will choose to compete, but he figures to be the king of the sporting world for as long as he does.
Mayweather will return to the ring on September 13, possibly in a rematch with Maidana who ran him close in Las Vegas last month.