A statement from tournament sponsors DGW Comunicacion revealed the event will "mark the return to the circuit of one of world tennis' top stars".
Nadal, 26, has been out of action since the middle of last season because of injury.
The former world number one was forced to miss the Australian Open because of a stomach virus while a succession of knee injuries have plagued his career.
Nadal, who has 11 Grand Slams to his name, had been widely expected to return to action in Acapulco, Mexico, at the end of February, two weeks after Sao Paulo.
Luis Felipe Tavares, chairman of sports company Koch Tavares, told Estado de Sao Paulo daily that "a name such as Nadal will definitely whip up a lot of interest".