It was a tough match at the end of a tiring tournament against the Belgians, who beat China by 22-5 to advance to the final.
Leading by 12-0 at the break, South Africa looked to be in control, but Belgium fought back to take a 14-12 lead before Libbie Janse van Rensburg scored the match-winner after the buzzer had sounded.
Ayanda Malinga handed the host nation a 7-0 lead after just 45 second when she over for the first try after a great switch of direction opening up space on the left, with Sizophila Solontsi giving a superb offload in the tackle to put the speedster away.
With little possession in the rest of the first half, the Bok Women failed to convert their few opportunities into points, but Solontsi eventually went over just before the break to hand SA a 12-0 lead.
From the restart though, Cecile Blondiau broke a few tackles to put Belgium on the board which was only the second try conceded by the Bok Women all weekend. Nele Pien's conversion made it 12-7.
Blondiau then scored another try for Belgium with the South Africans clearly tiring, and Pien's conversion handed them a 14-12 lead with three minutes to go.
However, Renfred Dazel's team had enough left in the tank and showed great character to allow Janse van Rensburg to crash over after the Belgians conceded a few penalties in the red zone, clinching a memorable win for South Africa, who won 11 and drew only one of their 12 matches in the two tournaments.
Ayanda Malinga scores against Czechia in the semi-final.
In the second semi-final, both teams were nervous at the start, turning over possession on a few occasions, but South Africa managed to keep Czechia pinned in their own half and when Ayanda Malinga was given space on the outside in the third minute, she didn't need a second invitation to score the opening try of the match.
That is how it stayed until the break, but with territorial advantage the South Africans were growing in confidence, leading by 5-0 at the end of the first half.
From the restart Simamkele Namba scored the second try after a strong run down the right by Rights Mkhari, after which the ball was quickly recycled and sent to the left where Namba straightened and raced away. Nadine Roos added the extras to make it 12-0 with six minutes to go.
Two minutes later Zintle Mpupha went over for South Africa's third try as Czechia struggled to control the restarts, handing the Bok Women attacking opportunities in their opponents' half of the field.
Roos converted to make it 19-0, and the playmaker then scored the fourth try from the restart - probably their best of the tournament so far - when she went over after a serious of brilliant offloads and interpassing which had the Czech defence at sixes and sevens.
Czechia had one last opportunity to attack from their own half, but a determined Roos chased down her opponent on cover defence to seal the 24-0 win, which was crucial as every point counts in these tournaments.
Before the final, South Africa hold a +210 points' difference from their 11 games, compared to Belgium's +124. The rules stated that if teams finish on the same number of total log points, overall points’ difference will be the first eliminator, but in the end it wasn't needed as the Bok Women finished the two weeks of rugby unbeaten.
