Mandela, who has been a free agent after his contract with another South African Premier Soccer League side Maritzburg United expired, was unveiled by the Masandawana on Thursday.
“The centre back comes with a wealth of international and local experience as he has played for Santos, the Team Of Choice and his national side,” the club said in a statement.
Mandela captained Kenya in their 2-1 win over Zambia in an international friendly match on October 9 in Nairobi.
Mandela first moved to South Africa in 2012 to join the now ABC Motsepe based Santos.
The move completes a remarkable comeback for the Harambee Stars player who is regaining form after a year out with a serious knee injury which forced him to miss the 2019 Africa Cup of Nations in Egypt.
This move also puts to bed earlier reports the Kenyan joined South African newbies Tshakuma Tsha Madzivhandila (TTM) FC.
The Limpopo Province-based side signed announced Onyango’s signing two weeks ago but the player played down talk in an interview with Nation Sport.
Owned by South African business magnate Patrice Motsepe, Sundowns are one of the accomplished football teams in Africa and boast of some of the best players on the continent including Ugandan goalkeeper Denis Onyango.
The team has won the league 13 times and also lifted Caf Champions League in 2016.