Cedarville is a village in Greene County, Ohio, United States. The village is within the Dayton Metropolitan Statistical Area. The population was 4,019 at the 2010 census.
Cedarville was originally known as Milford, and under the latter name was platted in 1816. A post office called Massies Creek was established in 1837, and the name was changed to Cedarville in 1843. The present name is for cedar trees near the original town site.
For many years beginning in the 1880s, public life in Cedarville centered around the downtown Cedarville Opera House; it survives to the present day, and is listed on the National Register of Historic Places.
Cedarville is located at 39°44′34″N 83°48′26″W (39.742796, -83.807084). According to the United States Census Bureau, the village has a total area of 1.32 square miles (3.42 km2), of which 1.28 square miles (3.32 km2) is land and 0.04 square miles (0.10 km2) is water.
As of the census of 2010, there were 4,019 people, 686 households, and 411 families living in the village. The population density was 3,139.8 inhabitants per square mile (1,212.3/km2). There were 759 housing units at an average density of 593.0 per square mile (229.0/km2). The racial makeup of the village was 94.4% White, 2.3% African American, 0.1% Native American, 1.1% Asian, 0.3% from other races, and 1.7% from two or more races.