Fairhaven is an unincorporated community and census-designated place (CDP) adjacent to Humboldt Bay in Humboldt County, California, United States. It is located 2.25 miles (3.6 km) west-southwest of downtown Eureka, at an elevation of 10 feet (3.0 m) above sea level. As of the 2020 census, Fairhaven had a population of 165.