Mamasa Regency is one of the six regencies that make up the West Sulawesi Province, Indonesia, on the island of Sulawesi. It covers a land area of 3,005.88 km2. Its capital is the town of Mamasa. The Mamasa people – which is a sub-group of the Toraja people – form the most common ethnic group.

Mamasa Regency is located at an altitude of 600-2,000 metres above sea level.