The 21-one-year made five PSL appearances this season for the club, and also played one domestic cup game.
Tau was also a part of the squad that competed in the CAF Champions League, and scored a goal in the loss against TP Mazembe in the DRC.
A source at the club told Sport24 that the management deemed it fit to give the youngster a professional three-year contract.
The source said that coach Pitso Mosimane has confidence in the youngster hence the new contract.
"Percy Tau has signed a new three year deal,” the Sundowns source confirmed.
“This is a professional contract because he was playing on a semi-professional contract last season, and now the club improved his contract to a three year professional one.”