More tennis players filled out the list behind out her. Caroline Wozniacki ($17.6 million), Sloane Stephens ($15.2 million), Garbine Muguruza ($15 million), Maria Sharapova ($14.3 million) and Venus Williams ($13.9 million) all enjoyed profitable financial years but it's Sindhu's name that really stands out.
The 23-year-old's purse was $11.6 million in the last financial year. Her prizemoney came in at $680,000 and sponsorships accounted for the rest, equating to a weekly wage of $223,000.
That's a helluva payday for someone even the most well-read sports fan wouldn't recognise in the street.
So how did a badminton player reach such lucrative heights?
Firstly, it turns out India isn't just obsessed with cricket — it reserves special status for those who make a living hitting a shuttlecock over a net, too. Or at least it does if that person was the first Indian female to win a silver medal at the Olympics.
Sindhu did just that at the 2016 Games in Rio de Janeiro, rising to prominence when she became the second badminton-playing Indian, male or female, to stand on the dais at an Olympics.
Arriving in Brazil as the ninth seed, upset wins over Chinese Taipei star Tai Tzu-ying, second seed Wang Yihan and sixth seed Nozomi Okuhara of Japan propelled Sindhu into the final.
She lost to World No. 1 Carolina Marin of Spain in the gold medal match but she won India's hearts — and dollars.
Before Rio, Sindhu had already won a bronze medal at the world championships — but in a sport not known for its worldwide appeal, that wasn't enough to ensure mainstream recognition.
Sindhu's commercial work is managed by Baseline Ventures, and managing director Tuhin Mishra said before the 2016 Olympics Sindhu was virtually unknown.
"Before the Olympics, when we reached out to sponsors, often we were asked, 'Sindhu who?'" Mishra told CNBC in 2017. "The market dynamics were tough. Everyone only wanted to be associated with cricket."
An Olympic medal changed all that.
Indian government agencies showered Sindhu with cash and land and cricket legend Sachin Tendulkar presented her with a BMW from the Hyderabad Badminton Association.
Endorsement deals from a host of companies — including Gatorade, Nokia and Panasonic — soon followed and she's made millions as an ambassador for roughly a dozen brands.
Those millions have seen Sindhu become the first Asian to crack the top 10 of the Forbes rich list since South Korean figure skater Kim Tuna in 2014.
"I'm absolutely thrilled to have been featured in this list," Sindhu told ESPN. "To be honest, bringing laurels to my country has always been my top-most priority and such accolades are by-products.
"My agency Baseline Ventures has done an amazing job in building my brand and I don't think I can thank them enough."
So how is Sindhu maintaining interest two years after grabbing silver in Rio? Well, winning helps.
She's since gone on to win more silver at the 2017 and 2018 world championships and at this year's Commonwealth Games on the Gold Coast, which has been key to her off-court success.
She might still be a way behind Williams when it comes to money-making capacity and everyday crossover appeal, but former India badminton star Aparna Popat put it best when describing the enormity of Sindhu's achievement.
"What makes this remarkable is that it's an Asian-dominated sport with not the kind of big money of West or US-centric sports that usually make such lists," she told ESPN.
"You have to remember that all of this is without even Sindhu becoming a World No. 1 or winning a world championship title. It just shows how big a sports personality she's worldwide today."
