The joint venture will commit to building 800 extra care facilities and operating them for 125 years.
Under the arrangement the council will supply the land and its new partners will design, build, operate and maintain the new accommodation.
The successful consortium will sell, let and manage the extra care schemes.
Derbyshire council is planning a £200m shake-up of adult care services.
Under the 10-year plan it will close 20 residential homes and replace them with 1,600 extra care flats, where health workers will be available 24 hours a day, seven days a week.