[2] In 2018, at the year's African Swimming Championships in Algiers, Algeria, Van Niekerk won a gold medal in each of the four events she competed.

[3][5] In the 100-metre breaststroke, she won her third gold medal of the Championships, finishing over eight-tenths of a second ahead of the silver medalist in the event with a time of 1:11.13.

[9][10][11] At the 2021 South Africa National Short Course Championships in Pietermaritzburg in September, Van Niekerk set two new African and South African records in the short course 50-metre breaststroke, first setting a mark of 30.06 seconds in the prelims heats, then lowering her records to a time of 29.85 seconds in the final.

[14][16] Van Niekerk swam faster than 1:07.00 in the long course 100-metre breaststroke twice at the 2022 Grand Prix international meet number two in Durban in February, first swimming a personal best time of 1:06.52 in the preliminary heats, then a 1:06.74 in the final.

[17][18] For the 2022 South Africa National Swimming Championships in Gqeberha in April, in part a selection meet to determine the 2022 World Aquatics Championships and 2022 Commonwealth Games South Africa team members, she entered to compete in the 50-metre breaststroke, 50-metre freestyle, 50-metre butterfly, and 100-metre breaststroke.

[32][33] In her first event of the 2022 World Aquatics Championships, the 100-metre breaststroke, Van Niekerk qualified for the evening semifinals with a time of 1:06.75 and rank of tenth from the preliminaries.

[37][38][39] She finished in a time of 29.99 seconds in the semifinals, qualifying for the final ranking third behind Benedetta Pilato of Italy and Rūta Meilutytė of Lithuania.

[53][54][55] Day four, Van Niekerk qualified for the semifinals of the 100-metre breaststroke with a 1:06.40 in the morning preliminaries, which was 0.70 seconds ahead of second-ranked Tatjana Schoenmaker.

[67] On day two of the 2022 World Short Course Championships in December, Van Niekerk ranked second in the preliminaries of the 100 metre breaststroke at the Melbourne Sports and Aquatic Centre with a personal best time of 1:03.93, advancing to the semifinals.

[71] The fifth morning, she ranked third in the preliminaries of the 50 metre breaststroke, setting a new African record with a time of 29.45 seconds and qualifying for the semifinals.

[73][74][75] She won the first silver medal for South Africa at the competition, and the second silver medal for South Africa in the female event following Penelope Heyns in 1999, in the final, finishing in a new African record time of 29.09 seconds.