Leo-Cedarville is a town located in the U.S. state of Indiana. It is within Allen County in Cedar Creek Township. It has a total area of 3.85 square miles at 41°12′54″N 85°0′56″W. The elevation is 797 feet above sea level. In 1838, Cedarville was platted, and Leo was established in 1849. As of the 2010 census data, it had a total population of 3,603. The population density was 1,014.54/sq mi.