It will be the two-time champion's first tournament in 14 months, since winning the 2017 Australian Open. She lost an exhibition to Jelena Ostapenko in United Arab Emirates on Dec. 30.
Williams reached the Australian Open semifinals in 2015 and the finals in 2016 after returning to the California event she had boycotted for years because of racial comments from the stands.
Top-ranked Simona Halep, defending champion Elena Vesnina, and former winners Maria Sharapova and Caroline Wozniacki are set to play. Also entered is Wimbledon champion Garbine Muguruza, U.S. Open winner Sloane Stephens, Karolina Pliskova, and Americans Madison Keys and Coco Vandeweghe.