As tipped in the Enquirer Willmott Dixon beat rival Kier to take on a £28m construction contract.
Work will now start on the project at the end of this month and see extensions to the east and west sides of the existing main hospital building.
The redevelopment will transform the independent hospital into a leading centre for health and wellbeing.
It will result in single bedrooms throughout, a new main entrance and glass roofed reception area, modernised theatres, and a new endoscopy unit.
Some of the work will be funded from land gain for 24 homes at the site.
Benenden Hospital is an independent trust hospital with charitable status. The hospital was originally built for the National Association for the Establishment and Maintenance of Sanatoria for workers suffering from Tuberculosis.
John Waterman, managing director for Willmott Dixon in the Southern Homes Counties said: “We are delighted to have secured this important contract with Beneden hospital.
“We have a strong local presence in Kent and our team are looking forward to creating a facility that will have a profound impact on supporting health and wellbeing in the region.”