Lionville is a census-designated place 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.