Chinese and Iranian warships were docked off South Africa's main navy base Thursday ahead of exercises that officials said were also meant to involve Russia.
The January 9-16 "Will for Peace" drill hosted by South Africa risks further straining its ties with the United States, which is in dispute with many of the countries taking part.
AFP journalists saw two Chinese ships in Cape Town's False Bay harbour on Wednesday, joined by an Iranian vessel on Thursday.
South African navy officials said warships from Russia were also expected to take part in the China-led exercises.
The drill was focused on the "safety of shipping and maritime economic activities", the South African defence force said in December when it announced the manoeuvres.
It was intended to "deepen cooperation in support of peaceful maritime security initiatives," it said.
The statement said the exercise would involve navies from BRICS countries.
President Donald Trump has accused countries in the BRICS group of emerging nations of "anti-American" policies.
South Africa has drawn US criticism for its close ties with Russia and a range of other policies, including its decision to bring a genocide case against Israel at the International Court of Justice over the Gaza war.
South Africa's military was criticised for hosting naval exercises with Russia and China in 2023 that coincided with the one-year anniversary of the Kremlin's invasion of Ukraine.