Arcadia is a city and county seat of DeSoto County, Florida, United States. Arcadia's Historic District is listed on the National Register of Historic …Arcadia is a city and county seat of DeSoto County, Florida, United States. Arcadia's Historic District is listed on the National Register of Historic Places. Its population was 7,420 as of the 2020 census, down from 7,637 at the 2010 census. It is the principal city of the Arcadia, Florida Micropolitan Statistical Area.