Banyana Banyana had been forced into the qualification route after their WAFCON quarter-final defeat by Morocco ended their chances of securing a direct place. Nigeria had also entered the play-off contest after suffering a loss to Cameroon the previous Sunday.
Desiree Ellis made one change to her starting line-up, handing Ronnel Donnelly her first start of the tournament in place of Isabella Ludwig.
South Africa dominated possession during the opening period but struggled to turn that control into clear chances, with Nigeria sitting deep.
Asisat Oshoala was also largely contained by the South African defence, and the teams went into the interval without a serious opportunity.
The deadlock was finally broken four minutes before the hour. Hilda Magaia raced down the left before picking out Thembi Kgatlana, who finished the move to register her third goal of the tournament.
Nigeria almost responded when Kanu headed towards goal in the 74th minute, but Kaylin Swart made an outstanding one-handed stop.
South Africa doubled their advantage with 13 minutes remaining as captain Refiloe Jane pounced on a loose ball and fired home a deflected effort.
Jane was dismissed in stoppage time for handball, allowing Uchiebe to score from the resulting penalty. South Africa will now prepare for the inter-confederation play-offs, which begin in November 2026, with five opponents from other confederations standing between Banyana and World Cup qualification.
Ghana edge out Ivory Coast to maintain play-off route to World Cup
Ghana kept their Women's World Cup hopes alive by beating Ivory Coast 2-1 in Casablanca on Thursday. Ivory Coast took an early lead when Ines Konan converted a penalty after a VAR review, but Princess Marfo levelled with a header before the hour mark.
Josephine Bonsu completed Ghana's comeback in the 72nd minute, calmly dispatching a spot-kick after a handball decision was upheld by VAR.
The result secured Ghana a place in Africa's intercontinental World Cup playoff route. The two winners from the WAFCON quarter-final losers' playoff will advance to the tournament's intercontinental qualifiers.
