During the 12-month period ending May 1, 2021 McGregor earned $250 million, a figure which includes $220 million from endorsements and the recent sale of the majority stake of his whiskey brand, Forbes said.
Barcelona and Argentina forward Messi was second on the list and set a record as the highest-earning football player after bringing home $181 million while Portugal and Juventus forward Ronaldo earned $168 million to sit third among the top 10 highest-paid athletes.
NFL quarterback Dak Prescott of the Dallas Cowboys and four-times NBA champion LeBron James rounded out the top five.
Forbes said its on-the-field earnings figures include all prize money, salaries and bonuses earned during the 12-month period while off-the-field earnings are an estimate of sponsorship deals, appearance fees and licensing income.