Mayweather, who is widely regarded as the best pound-for-pound boxer on the planet due to his 46-fight unbeaten record, tops the Forbes rich-list ahead of the Portugal international.
The 37-year-old, who is nicknamed ‘Money’, earned $105m (£62m) for his last two fights against Saul Alvarez and Marcos Maidana, while Ronaldo pocketed $80m (£47m) for his exploits with Los Blancos, although that figure also includes endorsement deals.
“I’m humbled and extremely fortunate to be recognised by Forbes as the highest-paid athlete once again,” he said in a statement.
“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.”