Kasilof ( kə-SEE-lof; Russian: Касилов) is a census-designated place (CDP) in Kenai Peninsula Borough, Alaska, United States. At the 2010 census the population was 549, up from 471 in 2000.
Kasilof is located at 60°20′7″N 151°14′1″W (60.335274, -151.233594). It is on the east side of the Cook Inlet on the Kenai Peninsula, on the Sterling Highway, 19 km (12 mi) south Kenai and 62 miles (100 km) north of Homer. It is bordered to the southwest by the Kasilof River, across which is the community of Cohoe. To the north, across Coal Creek, is the community of Kalifornsky.
According to the United States Census Bureau, the Kasilof CDP has a total area of 10.6 square miles (27.5 km2), of which 10.4 square miles (27.0 km2) are land and 0.2 square miles (0.5 km2), or 1.89%, are water.
Kasilof first appeared on the 1880 U.S. Census as an unincorporated village named "Kassilof." It appeared again in 1890, and in 1900 its name was shortened to the current spelling, Kasilof. It did not appear again on the census until 1930. In 1980, it was made a census-designated place (CDP).
As of the census of 2000, there were 471 people, 180 households, and 124 families residing in the CDP. The population density was 45.4 people per square mile (17.6/km²).