Four fire engines and around 25 firefighters and officers were called to a fire at a pub under refurbishment on Station Road, Edgware.
A small part of the roof was damaged by fire.
Watch Manager Kent Gayle, who was at the scene, said: "When we arrived, flames were visible from under the roof tiles.
"Crews worked quickly to bring the fire under control and prevented it spreading further inside the pub.”
The Brigade was called at 0407 and the fire was under control at 0605. Fire crews from Stanmore, Mill Hill and Hendon fire stations attended the scene.
The cause of the fire is believed to be accidental due to hot works on the roof.