A small blaze started in the laundry section of Chris Hani Baragwanath Academic Hospital on Sunday. The facility is near a COVID vaccination site.
Firefighters and security staff extinguished the blaze.
Officials suspect that the fire might have been triggered by a heater that was not switched off by one of the employees.
Operations at the facility are running normally, and the blaze was extinguished before it could spread to other parts of the hospital.
Senior officials were still at the scene at around lunchtime on Sunday, and they confirmed no one was injured.
This comes as authorities are still assessing the damage to the Charlotte Maxeke Hospital following a fire which forced its closure in April.
Thousands of patients have been affected and some were transferred to other facilities in the province including Chis Hani Baragwanath Hospital. Charlotte Maxeke has still not reopened.