Lavonia is a city in Franklin and Hart Counties, Georgia, United States. The population was 2,156 at the 2010 census, up from 1,827 at the 2…Lavonia is a city in Franklin and Hart Counties, Georgia, United States. The population was 2,156 at the 2010 census, up from 1,827 at the 2000 census. Lavonia is located in northeastern Franklin County at 34°26′10″N 83°6′23″W / 34.43611°N 83.10639°W. A small portion of the town extends southeast into Hart County.