Philo is a census-designated place in Mendocino County, California, United States. It is located 6 miles northwest of Boonville, at an elevation of 331 feet. The population was 319 at the 2020 census. Philo is located in Anderson Valley in western Mendocino County. Situated along Indian Creek as it flows into the Navarro River, Philo is the home of KZYX, the local public radio station.