Guests were evacuated from Wokefield Park near Reading in Berkshire last night (Wednesday) after a fire ripped through parts of the 18th-century hotel.
Firefighters were called to the scene at 17:30 after the fire broke out in a ground floor linen area and spread to the roof.
It is understood that the fire initially centred around the newer executive centre buildings (pictured).
Over 200 customers were evacuated from the three-star De Vere hotel, and overnight guests were taken by coach to nearby hotels. There were no reports of casualties.
The executive centre at which the fire took place has 222 bedrooms and 30 meeting rooms, as well as a pool, gym and sauna. The mansion house has 87 bedrooms, 21 meeting rooms and a restaurant.
Royal Berkshire Fire and Rescue group manager Chris Bunyan told the BBC that by midnight the fire had been under control.
He added: "There are six fire appliances still on site and crews are damping down and checking for hotspots.
"About 30 staff in total remain at the scene - I would say they will be there until at least three or four o'clock in the morning, with some there into the daylight hours."
De Vere said in a statement: "The fire broke out within a section of one of the buildings at Wokefield Park and a successful evacuation took place. The Fire Brigade were at the scene quickly and it was brought under control with no injuries.
"Whilst there has been damage to some the bedrooms in one of the buildings, a large proportion of the venue is unaffected and is back in operation today. We are in communication with all guests and any clients that may be affected."