Mick George Ltd was associated with the Earthworks, Notifiable Asbestos Management and Demolition of buildings, including the main chimney and water tower, podium section and basement.
Runwell Hospital was built in the 1930s and provided mental health services until closure in 2010.
The St Luke’s Park development of 575 homes will be built across 200 acres of former hospital grounds just north of Wickford.
The estate will also include shops, offices, and a community centre, plus a sensory and woodland garden. A carefully refurbished grade II listed chapel and other community facilities will also be created.