South African police recorded more than 4,000 cases between July and September, a two-fold increase on the same period last year.
The number of kidnappings today are "the highest ever in the history of South Africa," anti-crime activist Yusuf Abramjee told AFP.
"It has become an established and lucrative criminal practice," GI-TOC said in a report in September.
Most cases of kidnapping in South Africa are a side-effect of carjacking, robberies and rapes.
But, say crime experts, an increasing number of victims are now being targeted directly.
In one of the most high-profile cases, four sons of a South African businessman, aged between six and 15 years, were kidnapped Hollywood-manner while on their way to school.
In such cases, ransom demands can run into the millions of rand (tens of thousands of dollars).
Analysts say kidnappings have fueled by the involvement of foreign crime groups suspected to be operating from Mozambique and Pakistan, among others countries.
Indian business people, Pakistani, Somalians and Ethiopians are among those increasingly being targeted, according to Abramjee.
A Somalian businessman was recently snatched from a Johannesburg hotel lobby, he said.
Muslim families of Indian origin, who are rumored to hold large funds abroad, are especially at risk, said a police source.
Police last year set up a special unit and officials recently said they were "closing in on several syndicates" responsible for kidnapping for ransom cases.
Kidnappers sometimes brazenly demand that the ransom be paid into "foreign bank accounts via Bitcoin or via money exchanges in Dubai," said Abramjee.
But in other cases, the victim is simply killed after his bank account has been emptied.
One such fatality was Kevin Soal, a businessman in his late 60s with a passion for horse racing.
His luxury car was found abandoned in a township on the outskirts of Pretoria days later.
Soal's body was discovered afterwards in a nearby area with gun wounds police investigators reportedly say were consistent with an execution-style killing.
Large amounts of money had been withdrawn from his account, said a police source.
Police and private detectives are investigating the case.
Last month, the country was stunned when eight-year-old Abirah Dekhta was kidnapped on her way to school near Cape Town by five gunmen in two cars.
Missing-person posters showed a thin girl wearing a pink dress and matching headscarf.
She was freed during a spectacular police raid following a tip-off.
Dekhta had been held in a shack in the impoverished township of Khayelitsha, one of the largest in the country, guarded by seven men, police said. Her captors recently appeared in court, seeking bail.