Work is set to begin on site on 27th May 2014 and be complete by December 2016.
The hospital is privately-owned by Benenden Health.
The redevelopment will replaced wards with single bedrooms and provide a new main entrance with adjacent car park and drop off area. The outpatient area and theatres will be modernised and a new endoscopy unit added.
Willmott Dixon regional managing director John Waterman said: “We are delighted to have secured this important contract with Benenden 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.”