Southworth is an unincorporated community and census-designated place (CDP) on Puget Sound in Kitsap County, Washington, United States. It is best known for being the west end of the Fauntleroy-Vashon Island-Southworth Washington State Ferries run. Landmarks include Southworth Grocery, a US Post Office, ferry terminal, clay cliffs and a private beach on the point. Next to the ferry is a popular place to launch kayaks for trips to nearby Blake Island. The population of the Southworth CDP was 2,185 at the 2010 census.