Four fire engines and around 25 firefighters tackled a flat fire on Fulham Palace Road in Fulham.
Part of a five-roomed flat on the third floor of a residential block was damaged by fire. There were no reports of any injuries.
The fire is believed to have been accidental and caused by sunlight reflecting onto combustible items.
A London Fire Brigade spokesperson said: “These sorts of fires are not as rare as you would think. They can happen all year around, but as we head into summer and the sun gets stronger, it’s really important that reflective items such as mirrors, crystals and glass ornaments are kept out of direct sunlight.
“Firefighters also recommend that you have a look at our online Home Fire Safety Checker to make sure there are no hidden hazards in your home.
"The online tool will ask you a series of questions that will help us work out the level of risk in your home, or the home of someone you care for. It only takes a few minutes to get tailored advice to keep yourself and loved ones safe from fire.”
The Brigade’s Control Officers were called at 1548 and mobilised crews from Chiswick, Wandsworth, Fulham and Chelsea fire stations to the scene. The fire was under control by 1656.