Six fire engines and around 40 firefighters were called to a fire at a pub on Stamford Street in Southwark.
A small part of the first floor and part of the extraction system from the first floor to the roof of the building was damaged by fire.
The Brigade's Fire Investigators believe the cause of the fire involved an electric deep fat fryer. There were no reports of any injuries.
Station Commander David Bracewell, who was at the scene said: "The road was closed between Blackfriars Bridge and Waterloo Roundabout whilst crews worked to make the scene safe.
"We'd like to remind restaurant and takeaway owners to make sure that they don't have dirty ducting. If you don't clean your extraction system regularly, you're at a greater risk of ducting fires."
More information on using deep fat fryers safely
The Brigade was called at 1248 and the fire was under control by 1443. Fire crews from Lambeth, Dockhead, Soho, Brixton and Whitechapel fire stations attended the scene.