More than 40 personnel and six fire appliances were involved in the operation on the Lisburn Road from just after 2.20pm on Tuesday.
The fire had been brought under control by around 5pm.
The Northern Ireland Fire and Rescue Service said the cause of the blaze is believed to have been accidental.
“At 14.22hrs, the Northern Ireland Fire and Rescue Service were called to a report of a fire on the roof of a four-storey building on the Lisburn Road, Belfast,” a spokesperson said.
“Six fire appliances, one aerial appliance and one command support vehicle attended the scene.
“The fire was brought under control at 17.07hrs by firefighters using breathing apparatus and wearing specialist working at height equipment. The cause of fire was identified as accidental.”