Semenya closed out a superb campaign last week with her maiden victory in an international 400m race at the IAAF Diamond League final in Brussels, clocking a career best of 50.40 seconds, after winning the 800m race at the penultimate leg of the series to lift the overall crown in the two-lap event.
The former world champion had charged to Olympic gold in Rio last month in a national record 1:55.28 and remains unbeaten in her specialist discipline this year.
Van Niekerk, meanwhile, delivered a stunning performance, bagging Team SA's only other gold medal at the Rio Games.
The 24-year-old sprinter had opened his season with a 9.98 victory over 100m at the Free State Athletics Championships in Bloemfontein in March, becoming the first man to run under 10 seconds (100m), 20 seconds (200m) and 44 seconds (400m) in a career.
At the Olympics, he set a 400m world record of 43.03, taking 0.15 off the 16-year-old global best previously held by American great Michael Johnson, further establishing his place among the fastest men in the world.
In other events, Luvo Manyonga produced the performance of his life to take the Men's Long Jump silver medal at the Games, just one centimetre short of gold, and he went on to set a Personal Best of 8.48m for victory at the Diamond League final in Brussels.
Sunette Viljoen, who narrowly missed out on a Javelin Throw medal at the 2012 London Olympics, approached her best form in Rio, also earning silver.
The two-time World Championships bronze medallist was ranked eighth in the world this year with a best heave of 65.14m set in Doha in May.
Speedster Akani Simbine enjoyed a breakthrough season, finishing fifth in the 100m Men final in Rio (0.03 outside a podium place) after setting a national record of 9.89 at a meeting in Hungary in July.
Earlier in the year, middle-distance runner Elroy Gelant had clocked a new SA 5 000m Men record, covering the distance in 13:04.88 in Hengelo in May.
Lebogang Shange set a national mark of 1:20:06 in the Men's 20km Walk in Adelaide in February, and Anel Oosthuizen recorded a new SA standard of 1:34:49 in the Women's event in Podebrady in April.
