South Northamptonshire is a district in Northamptonshire, England. Its council is based in the town of Towcester, first established as a settlement in Roman Britain.

The largest town in the district is Brackley, which had a population of 14,000 in 2008 followed by Towcester which has a population of nearly 10,000. Other significant settlements in size include Deanshanger, Bugbrooke, Roade, King's Sutton, Silverstone and Middleton Cheney. Many of the villages listed have populations exceeding 1000.