Sundowns recently recruited the Brazilian along with Thapelo Morena, Sibusiso Vilakazi and Lucky Mohomi.
Nascimento could make his debut for Downs in Sunday's MTN8 quarter-final with Tshwane rivals SuperSport United at Loftus Versveld Stadium.
"He has received his papers. He is available for selection," club spokesperson Thulani Thuswa tells snl24.com/kickoff.
The 29-year-old received his paperwork too late to be registered for the side's African Champions League campaign.
Pitso Mosimane's men will play Nigeria's Enyimba this evening in the CAF showpiece in Port Harcourt, having already qualified for the semi-finals of the event.