Serena Williams who was back from her long pregnancy break topped the list with the earnings of $18.1 Million.
Williams, who will try to equal Margaret Court's record of 24 grand slam titles when she competes at the August 27-September 9 U.S. Open in NY, earned twice as much off the court as any other female athlete, according to Forbes.
In June, Forbes issued a ranking of the world's 100 highest-paid athletes did not feature any woman.
And then there's her game, worryingly inconsistent in six tournaments so far this year - including the French Open where she withdrew before the fourth round with a pectoral injury.
Eight of the top 10 highest earning female athletes are tennis players, with 23-time Grand Slam champion Serena Williams topping the Forbes list.
The only non-tennis players in the top 10 are Indian badminton star P.V. Sindhu $8.5m (R122m) and racing's Danica Patrick $7.5m (R108m).
Top seed Halep faces Estonia's Kaia Kanepi while Danish world number two Caroline Wozniacki meets former U.S. Open victor Samantha Stosur of Australia in the first round, with another champion, Russia's 2004 victor Svetlana Kuznetsova, drawn against 16th-seeded Venus in her opener.
World number one Simona Halep arrives at Flushing Meadows buoyed not only by her first Grand Slam title at Roland Garros but by an impressive hardcourt campaign that included a victory in Montreal followed by a runner-up finish in Cincinnati.
Defending men's champion and top seed Rafael Nadal, who past year won his third title at Flushing Meadows, will play fellow Spaniard David Ferrer in the first round.
This marks Serena's return to Flushing Meadows after missing the hard-court tournament in 2017 - she gave birth to her daughter last September 1.
Williams, seeking to tie Margaret Court's record of 24 grand slam titles, comes into the Open after a frosty Open-tuneup season.
As such, Williams, 36, still is on course to face a top-16 seed in the third round in her first Open as a mother.
Venus, who won five of her seven Grand Slam singles trophies in NY, is ranked and seeded 16th.