Mohafe was axed lat week following a poor start to the Betway Premiership season, with Trevor Mathiane as caretaker coach at the weekend when Gallants fell to a 1-0 defeat away against AmaZulu.
Gallants sit bottom of the league table having only collected two points from six matches in the current campaign, with two draws and four losses.
Kanalelo was previously in charge of Namibian club African Stars, who he guided to a upset win in the first preliminary round of the CAF Champions League on Saturday after beating Gabon outfit 2-0.
The 55-year-old Kanalelo, also a former assistant coach to the Namibia national team, was a member of the Sundowns squad between 1997 and 2004 as back-up to first-choice goalkeeper John Tlale.
He helped Masadawana win three consecutive league titles from 1998 to 2000 and was part of the team that lifted the Bob Save Super Bowl in 1998.
Kanalelo's first game in charge at Gallants will be on Sunday when they host defending league champions Orlando Pirates at the Royal Bafokeng Stadium.