Barnwell
- County:
- Barnwell County
- County Seat:
- No
- Area (mi²):
- 7.842
- State:
- South Carolina
Barnwell is a city located in Barnwell County, South Carolina. Barnwell has a 2026 population of 4,589. Barnwell is currently growing at a rate of 0.11% annually but its population has decreased by -1.31% since the most recent census, which recorded a population of 4,650 in 2020.