It is located in the province of Western Finland and is part of the Southwest Finland region. The municipality has a population of 10,827 (31 January 2019) and covers an area of 242.26 square kilometres (93.54 sq mi) of which 3.89 km2 (1.50 sq mi) is water. The population density is 45.42 inhabitants per square kilometre (117.6/sq mi). The municipality is unilingually Finnish.
Paimio is best known for Paimio Sanatorium operating as a part of Turku University Hospital. It was built in 1932 and designed by architect Alvar Aalto and originally served as a tuberculosis sanatorium.