The Office of the County Administrator was created by the McLean County Board in 1975 to administer the policies and decisions of the Board. Major responsibilities include: preparation of the annual budget; maintenance and enforcement of Board policies, including personnel policies' coordination of all departments; and research and planning related to the County budget and other areas, as determined by the County Board.

The County Administrator also represents the County in an administrative capacity and conducts the day-to-day business of the County. Under the direction of the Board, the Administrator promotes intergovernmental cooperation and provides those administrative services which may be centrally administered.