Sandomierz Basin (Polish: Kotlina Sandomierska) is a lowland, located in southeastern Poland, between the Lesser Poland Upland, Lublin Upland and the Western Carpathians.

Its name comes from the historical city of Sandomierz, and the basin has a triangular shape with the size of around 15,000 km2 (5,800 sq mi).

Among major cities located in the Sandomierz Basin are Dębica, Jarosław, Mielec, Przemyśl, Przeworsk, Rzeszów, Stalowa Wola, Sandomierz, Tarnobrzeg, and Tarnów.

The basin is divided into the following geographical subregions: The basin is rich with natural resources, such as salt (Bochnia, Wieliczka), gypsum, sulphur (Tarnobrzeg), natural gas (Husow, Jarosław) and petroleum.

It is crossed by European route E40, along which goes a main west–east rail line from Kraków to Lwów.