Beacon Hill is an unincorporated community and census-designated place (CDP) in Cowlitz County, Washington, United States. As of the 2020 census, it had a population of 2,211. During the 2010 census, Beacon Hill was part of the West Side Highway CDP. The CDP is in the western part of the county and is bordered to the south and west by Longview Heights, to the northeast by Lexington, and to the east by the Cowlitz River. State Route 411 runs through the east side of the community, following the Cowlitz. It leads south 3 miles (5 km) to Longview and north 9 miles (14 km) to Castle Rock.