Tshilo, who was earlier reported as seeking a move overseas, has penned a two-year contract with the Brazilians who are also on verge of signing Platinum Stars midfielder Tsepo Ramokala.
Downs communication manager Alex Shakoane confirms that ‘Chappies' will be wearing the club's colours next season.
"Yes, he is now our player. It's a done deal."
The arrival of the Amabinneplaas defender at Chloorkop is set to spell doom for defender Robyn Johannes who has indicated that he wants a move out of Sundowns due to limited game time.
The Patrice Motsepe owned side have already signed central defender Method Mwanjali from Caps United in Zimbabwe.
Another new signing for the Brazilians ahead of next season is Zimbabwean national team striker Nyasha Mushekwi.