Hayti (pronounced "HAY-tie") is a town in Hamlin County, South Dakota, United States. The population was 381 at the 2010 census. It is part of the Watertown, South Dakota Micropolitan Statistical Area. It is the county seat of Hamlin County.
Hayti is located at 44°39′27″N 97°12′16″W / 44.6575°N 97.20444°W / 44.6575; -97.20444 (44.657591, -97.204391).
According to the United States Census Bureau, the town has a total area of 0.3 square miles (0.7 km²), all of it land.