The 34-year-old man distributed the pornographic images to police officers and to the public on social media, police said.
The arrestee is expected to appear in court on Tuesday to face charges of contravening the country's Cyber Crimes Act, which relates to unlawfully accessing or processing of computer data.
Police spokesperson Philani Nkwalase told TimesLive, a South African online newspaper, that the investigation started in May when the images were first distributed. The man was traced to the eastern city of Pietermaritzburg, where he was arrested. "His device that was allegedly used as well as sim cards were recovered in his possession,” Nkwalase said.
Pornography is legal in South Africa, although its distribution is restricted.