The three officials who comprise the St. Joseph County Board of Commissioners are elected from and represent separate districts for a term of four years. These districts must be redrawn once every ten years.

The Board of County Commissioners serve as the executive and administrative authority for the county. It operates and maintains all county facilities and property; negotiate contracts; permits all purchasing and claim payments; receives bids for construction projects and maintenance of roads and bridges; makes appointments to certain board and authorities; oversees certain election functions; prepares the annual county budget and serves on the Board of County Finance.