Lionville is a census-designated place (CDP) in Uwchlan Township, Chester County, Pennsylvania, United States. The population was 6,189 at the 2010 census. Prior to 2010 the CDP was recorded as Lionville-Marchwood. "Marchwood", however, refers only to the housing development begun in the early 1960s that is located south of the 100-113 intersection.
Lionville is bisected by two major local highways, PA 100 and PA 113. The area contains residential neighborhoods, hotels, restaurants, and other businesses. 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 borough of 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 during the American Revolutionary War.
Lionville has an independent zip code and post office, but 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 businesses use the Exton name instead, especially if they do not have other locations in the area.