About 70 firefighters helped tackle a blaze at the Grove House, Camberwell, when fire broke out on Sunday night (22 July).
Some 50 people were evacuated from the Ram Pub Company property, with no injuries reported.
The London Fire Brigade said six people were also evacuated from a nearby building as a precautionary measure.
Ten fire engines, including crews from Peckham and surrounding districts, were called to the scene.
The building’s first and second floors were affected, with additional damage to an extraction system from the first floor to the roof.
Fire officials believe the fire was caused by a thermostat failing on a deep fat fryer, causing the oil to catch alight.
It took almost six hours to bring the blaze under control, with services called at 8.40pm and the fire under control shortly after 2am.
A statement on the pub’s website said it hopes to open its doors again soon.
It read: “Due to a fire in the upper two floors we have had to close the pub, we are currently working with our insurers to get the pub back up and running as soon as possible.
“We would like to take this opportunity to thank London Fire Brigade for their quick response and professionalism in bringing the fire under control.
"We hope to see all of you again in the near future."
Station manager Andy Walton said: “Crews worked hard in challenging and humid conditions to bring the fire under control, preventing lateral fire spread to neighbouring properties.”
The pub added on its Facebook page: “The pub will be closed until further notice due to fire. Apologies for any inconvenience."