Williams held the title for the past four years but this year she earned $1.4 million less than Osaka.
The 23-time Grand Slam winner ranks no. 33 while Osaka was a few slot ahead at no. 29 on the list of 100 highest paid athletes.
Osaka has earned $14.5 million in prize money and has raked in millions from her 15 endorsement deals which include Nissan, Citizen Watches, cosmetics company Shiseido, Yonex (whose tennis rackets she uses), and Nissin Foods.
Osaka started making history in tennis at the tender age of 20 after she won the U.S Open against Williams.
She became the first Asian tennis player to ever be in the no. 1 slot when she won the Australian Open in 2019 and the first Japanese player to win a Grand Slam in her match against Williams.