The Black Eyed Peas frontman, 36, was photographed calmly covering his face with a T-shirt as he was escorted out of the burning 28-story Park Lane Hilton.
In town for business, the pop star had a performance scheduled for the evening with his band mates at Hyde Park, close to where the fire took place. He later Tweeted from the performance.
At least 20 firefighters were on the scene once news of the disaster broke. According to reports, no one was injured, but there were at least 1,500 guests and staff who fled the property.
No official cause of the fire has yet been released, but it reportedly began on the second floor in the kitchen.