100 guests were evacuated from the Marylebone five-star, which is an A-list favourite counting the likes of Lady Gaga, Tom Cruise and Johnny Depp as regulars.
Owner Andre Balazs has said that the cause of the blaze was as-yet unknown, but the fire services were investigating.
“We are grateful to confirm that no one was hurt, and our guests and staff safely evacuated,” he added.
According to the London Fire Brigade, the fire started in ducting and spread from the ground floor to the roof of the four-storey hotel.
The venue had been due to hold a Netflix-sponsored BAFTA after party on Sunday (16 February).
Located on Chiltern Street, Chiltern Firehouse occupies the site of a Victorian fire station built in 1889.
In 2013 the Chiltern Firehouse opened as a 26-suite hotel and 200-seat restaurant that was at the time helmed by Nuno Mendes.
The restaurant is currently overseen by head chef Luke Hunns offering a ‘fresh menu of reimagined classics and bold new flavours, placing emphasis on seasonality and healthy eating’.