Barnack is a village and civil parish located in the north-west of the Peterborough unitary authority within the ceremonial county of Cambridgeshire, England. It is situated in the historic county of Northamptonshire, approximately 4 miles (6.4 km) south-east of Stamford, Lincolnshire.
The parish includes the hamlet of Pilsgate, which lies about 1 mile (1.6 km) northwest of Barnack. Both locations are positioned along the B1443 road. According to the 2021 Census, the population of the parish was recorded at 1,000 residents.