The Board of Sumter County Commissioners is the legislative and governing body of the county. Sumter County is a "Constitutional County", meaning that authority to operate is derived directly from the Constitution of the State of Florida and not from a locally adopted charter.

There are five single member district commissioners, each elected from one of five geographic areas of the county. Each commissioner must reside in the district he represents. Commission terms are four years. The terms of Districts 2 and 4 are staggered with the terms of Districts 1, 3, and 5.

The Board selects a Chairman from among the members and a Vice-Chairman, who presides over the Board in the absence of the Chairman.

Chapter 125 of the Florida Statutes establishes numerous specific duties of County Commissioners. Generally, the Board adopts ordinances (local laws) and resolutions, which establish policies and programs to protect the health, safety, and general welfare of the citizens of the county. The Board adopts an operating budget for the functions of county government.

The Sheriff, Clerk of Circuit Court, Supervisor of Elections, Property Appraiser, and Tax Collector are elected countywide. Their duties are set forth in the Florida Constitution and Florida Statutes. Funds to operate their departments come from the County Budget.

The County Commission appoints the County Administrator to carry out executive responsibilities. The duties of the County Administrator are established in the Florida Statutes and local ordinances. Under the direction of the County Administrator, county commission departments provide a variety of local government services, information, and programs.