Camarillo is a city in Ventura County in the U.S. state of California. As of the 2010 United States Census, the population was 65,201, an increase of 8,117 from the 57,084 counted in the 2000 Census. Camarillo is named for brothers Juan and Adolfo Camarillo, prominent Californios who owned Rancho Calleguas and founded the city. The city is home to California State University, Channel Islands, housed on the former grounds of the Camarillo State Hospital.