Sauvo (Swedish: Sagu) is a town and municipality in the region of Lounais-Suomi in Finland. It is located in the Southwest Finland region. The municipality had a population of 2,985 (31 January 2019) and covers an area of 299.47 square kilometres (115.63 sq mi) of which 47.21 km2 (18.23 sq mi) is water. The population density is 11.82 inhabitants per square kilometre (30.6/sq mi).
Like many waterside areas near major population centres, Sauvo's population increases every summer because of summer cottage usage. While vacationers are not reflected in the official statistics, they roughly double the population during the summer. Today it holds a stone church from the late 15th century, and many manor houses.
The municipality is unilingually Finnish.