Ronaldo ranks among the three top-earning athletes for a sixth straight year after receiving $108 million (R1.37 billion) over the past year.
Salaries and prize money are up significantly, but endorsement earnings fell for the second straight year to $ 877 million as companies watch their sports marketing budgets.
Serena Williams, victor of 23 grand slam tennis singles titles, was the sole female representative past year but she has since largely been inactive owing to pregnancy and following the birth of her daughter Alexis in September.
Mayweather earnt $275m (£205.9m) from his fight against UFC star Conor McGregor last August and supplemented his annual income with $10m (£7.49m) in endorsements, Forbes reports.
Boxer Floyd Mayweather reclaimed his place at the top of Forbes' annual ranking of the 100 highest-paid athletes.
Lionel Messi and Cristiano Ronaldo both earn around the £80million per year mark, though one star does rank higher than the other.
Afghan security forces repel attack from gunmen dressed as United States soldiers
It is unclear who carried out the attack, though the southern province is the Taliban's historic heartland. The violence left at least four security forces members dead, according to officials.
Mayweather stood firmly atop the list having earned $285 million dollars, most likely all related to the bout with McGregor.
Players from 11 different sports are featured in the list, and from 22 different countries.
This year 40 National Basketball Association players made the cut in Forbes' annual look at the world's 100 highest-paid athletes, breaking the record of 32 set last year by hoopsters.
Tiger Woods is one of only three athletes to have topped the Forbes Richest Athletes list.
The top 100 athletes earned a total of US$3.8bn, up 23% from previous year, Forbes said.
NBA stars lead with a record-topping 40 basketball players among the top 100.
Atlanta Falcons quarterback Matt Ryan is the highest earning National Football League player, coming in at ninth with $88 million.