The top 100 includes athletes from 25 countries and their $5.96 billion combined earnings are up 5 per cent from the previous year when American boxer Floyd Mayweather was first with $430 million.
The magazine takes money, salaries and endorsements from athletes between June 2018 and June 2019 to break down its list, which has been published every year since 1990.
His only fight since August 2017 was an exhibition boxing bout against Japanese kickboxer Tenshin Nasukawa in December. Barcelona legend Andres Iniesta is next footballer on the list (46th overall), having earned $32.5 million.
And Messi was named the highest paid athlete for the first time, moving one position from a year ago thanks to a staggering earnings of $127m (R1.87bn).
Athletes from 10 sports made the top 100, with National Basketball Association stars leading the way.
Messi was one of 38 non-American athletes on the list, with 62 United States stars in the top 100.
For the second successive year, Lionel Messi sits above arch-rival Cristiano Ronaldo in Forbes' latest rich list, ranking as the best-earning footballer across the globe. The NBA accounted for the most athletes with 35.
Los Angeles Lakers star LeBron James was the highest earning National Basketball Association player, with $89 million, while Golden State's Stephen Curry was ninth with $79.8 million.
On the list this year, the three footballers are followed by Mexican boxer Saul "Canelo" Alvarez, with earnings in the order of 83 million euros, and Swiss tennis player Roger Federer, with a revenue of 82.5 million euros. The Paris Saint-Germain and Brazil star earned a total of $105 million. Aaron Rodgers (NFL player) $134 million 8.