Champneys has acquired Eastwell Manor hotel in Kent to create a resort spa.
The 62-bedroom hotel will undergo a refurbishment programme which is due to be complete by Summer 2017. It will operate the title Champneys at Eastwell.
The hotel, with origins dating back to the Norman conquest, includes two restaurants, a spa and leisure facilities.
Champneys has already made investments in Champneys Forest Mere and Champneys Tring in the past 12 months. The group, which operatesd four resort spas and six city spas, is also planning further upgrades at Champneys Henlow and Champneys Springs.
Champneys owner Stephen Purdew said: "The acquisition of Eastwell Manor is a major milestone for the Champneys group.
"As the original pioneers of health spa resorts in the UK we are delighted to be welcoming such a landmark property to the group and for Eastwell Manor to develop its own wellness credentials.
"We are continuing to look at our future growth and with recent investments in our signature properties we are very excited about wellbeing in the UK."