According to the entity, the additional dose will be administered to people over 18 years of age who received the initial single dose.
As stipulated, the second J&J dose should be given at least two months after the first one.
SAHPRA has also decided to approve the mixing and matching of different Covid-19 vaccines.
Those who received Pfizer-BioNTech’s two-dose vaccine may also be eligible to receive a third dose of J&J’s vaccine, in what is known as a heterologous boost, SAHPRA says.
At the moment, the South African Ministry of Health has not ruled on this option.
The dosing interval for the heterologous booster dose (J&J) will be six months after Pfizer’s second injection, the regulator said.
Over 6.8 million people, including healthcare workers, have already been vaccinated in South Africa with the J&J vaccine.