The new facility at the central Kansas military base will replace the 50-year-old Irwin Army Community Hospital.
The project includes a 263,000-square-foot hospital, a 289,000-square-foot clinic, a central energy plant, an ambulance garage and support facilities.
Construction is scheduled to begin this fall and completed by spring 2012.
Walton president Dennis Thompson says between $750 million and $1 billion in construction work has been completed at the base in recent years.
Walton's largest project there so far was a $135 million barracks complex.