Kenai Peninsula Borough is a borough of the U.S. state of Alaska. As of the 2010 census, the population was 55,400. The borough seat is Soldotna.
The borough includes the entirety of the Kenai Peninsula and a few areas of the mainland of Alaska on the opposite side of Cook Inlet.
The borough has a total area of 24,752 square miles (64,110 km2), of which 16,075 square miles (41,630 km2) is land and 8,677 square miles (22,470 km2) (3.4%) is water.
There is a Borough-wide government based in Soldotna, consisting of a strong mayor and an assembly of representatives from all areas of the Borough. They collect sales and property taxes and provide services such as road maintenance, waste collection facilities, emergency services and major funding for public schools. Incorporated towns also have their own local governments and city councils. The Alaska Department of Corrections operates the Spring Creek Correctional Center near Seward and the Wildwood Correctional Complex near Kenai.