Lionville-Marchwood is a census-designated place (CDP) in Uwchlan Township, Chester County, Pennsylvania, United States. The population was 6,298 at the 2000 census. Lionville is bisected by two major local highways, PA 100 and PA 113. The area contains residential neighborhoods, hotels, restaurants, and other businesses. While the census designation is Lionville-Marchwood, Lionville is officially the village that is part of Uwchlan Township. Marchwood refers only to the housing development begun in the early 1960's that is located south of the 100-113 intersection. The original name of the village was Welsh Pool but to honor the local Red Lion Inn the name was changed to Lionville, since a Red Lion, Pennsylvania, already existed. The area of Lionville along Village Avenue is a protected historic district. The Friends Meeting House was used as a hospital by the Continental Army. Lionville has an independent zip code, and post office, however it has never had mail delivery. Many of the long-term residents who picked up mail at the now closed general store, or fire station, locations now use a Downingtown address. Because much of the area also falls under the Exton zip code, many Lionville-Marchwood businesses use the Exton name instead, especially if they do not have other locations in the area.
Lionville-Marchwood is located at 40°3′10″N 75°38′43″W / 40.05278°N 75.64528°W / 40.05278; -75.64528 (40.052833, -75.645237).
According to the United States Census Bureau, the CDP has a total area of 2.5 square miles (6.4 km²), all of it land.