Prestonsburg is a city in the United States. It is the county seat of Floyd County in the state of Kentucky. The city is in the Eastern part of Kentucky. Prestonburg is on the bank of the Big Sandy River. The area was fist settled in 1797 by Colonel John Preston, Solomon Stratton, Matthias Harman, and Andrew Hood. It is named after Colonel Preston. In 2010, 3,255 people lived in the city.