South Ormsby, sometimes called South Ormesby, is a village in the East Lindsey district of Lincolnshire, England. It is situated west from the A16 road, south from Louth and 7 miles north-east from Horncastle. With the nearby hamlet of Ketsby, it forms the civil parish of South Ormesby with Ketsby.
The 15th-century church of St Leonard's is approached by a short climb up a path next to the old school house.
Ormsby Hall, built by James Paine in 1752, stands in a wooded parkland complete with lake.
The village has a public house, the Massingberd Arms, and a motor repair garage.
The Greenwich Prime Zero meridian line passes through the village.