Philomath is a city in Benton County, Oregon, United States. It was named for Philomath College. The population was 4,584 at the 2010 census and was most recently estimated in 2019 to have a population of 5,666. It is part of the Corvallis, Oregon, Metropolitan Statistical Area.

Benton County is one of the 36 counties in the U.S. state of Oregon. As of the 2020 census, the population was 95,184. Its county seat is Corvallis. The county was named after Thomas Hart Benton, a U.S. Senator who advocated American control over the Oregon Country. Benton County is designated as the Corvallis, OR Metropolitan Statistical Area, which is included in the Portland–Vancouver–Salem, OR–WA Combined Statistical Area. It is in the Willamette Valley.