Work will get underway early next year to provide new operating theatres at Darlington Memorial Hospital.
The contract also covers improvements to the recovery suite, the day surgery facilities and the associated post and pre-operative ward areas.
Anthony Dillon, managing director for Willmott Dixon in the North said: “Willmott Dixon will utilise its national experience of working within a busy hospital environment to help CDDFT realise its plan for improved facilities at Darlington.
“The focus will be to ensure that construction work does not disrupt the hospital’s day-to-day activities.”
Completion of the project is due in 2016.