A report found that one third of adults used the internet and two-thirds of these spoke an African language at home.
Lead researcher Indra de Lanerolle said in a statement that the study indicated a "new wave" of internet users had emerged in recent years.
"Their presence is something that business, government, political parties, and civil society should be responding to."
In 2008, only 15% of South Africans used the internet, but the survey found this had risen to 34% in 2012. At this rate, more than half the adult population would be using the internet by 2014.
Fifty-two percent of first-time users accessed the internet from their phones and four out of 10 internet users survived on less than R1 500 per month.
One of the greatest barriers to internet use was low levels of English literacy.
About one-fifth of South African adults could not read or write English with ease, and three percent of these were internet users.
The internet needed to become more multi-lingual to cater to this potential audience, De Lanerolle said.