The list pays tribute to the most stylish athletes in sport, including stars at the top of their games in tennis, basketball, football, golf and more.
This year's Fashionable 50 Sports Illustrated magazine cover has been graced by Williams, who just missed out on clinching her 24th Grand Slam title following her Wimbledon women's singles final loss to Simona Halep on Saturday.
Williams has made a name for herself both on the court and the catwalk, having announced the launch of her first solo clothing line in May last year.
Also on the list is celebrated professional basketball player LeBron James.
While James' fans will be most used to seeing the athlete in his Los Angeles Lakers jersey, the athlete also knows how to work a cool, casual, off-court look.
"Dressing his 6'8", 250-pound frame is no small task, but King James has mastered game-day dressing with expert tailoring, cool accessorising and a polished mixing-and-matching of fabrics patterns and colours," Sports Illustrated states with regards to the 34-year-old.
Five-time Grand Slam winner Maria Sharapova also made the list, due to the "elegant aesthetic" she regularly displays.
On 24 February, the tennis player attended the Vanity Fair Oscars after-party in Beverly Hills, California.
The 32-year-old wore a metallic pleated mini dress by French fashion house Lanvin, accessorising with silver, dangly earrings and black, strappy heels.
Sharapova had her hair styled in an updo, placing further emphasis on the intricate design of the dress.
Other stars featured on the Sports Illustrated Fashionable 50 list include Formula One driver Lewis Hamilton, footballer Cristiano Ronaldo, FIFA Women's World Cup winner Ashlyn Harris and alpine ski racer Lindsey Vonn.
For the full list of Sports Illustrated's Fashionable 50, click here.