Kelseyville is a census-designated place (CDP) in Lake County, California, United States. Kelseyville is located six miles southeast of Lakeport, at an elevation of 1,384 feet. The population was 3,353 at the 2010 census, up from 2,928 at the 2000 census.

Lake County is a county located in the north central portion of the U.S. state of California. As of the 2020 census, the population was 68,163. The county seat is Lakeport. The county takes its name from Clear Lake, the dominant geographic feature in the county and the largest non-extinct natural lake wholly within California.