West Farmington is a village in northwestern Trumbull County, Ohio, United States, along the Grand River. The population was 542 at the 2020 census. It is part of the Youngstown–Warren metropolitan area.

Trumbull County is a county in the far northeast portion of the U.S. state of Ohio. As of the 2020 census, the population was 201,977. Its county seat and largest city is Warren, which developed industry along the Mahoning River. Trumbull County is part of the Youngstown–Warren, OH Metropolitan Statistical Area.