Uusikaupunki (Finnish pronunciation: [ˈuːsiˌkɑupuŋki], Swedish:Nystad), is a town and municipality of Finland.

It is located in the Southwest Finland region. The municipality has a population of 15,469 (31 March 2016) and covers an area of 551.65 square kilometres (212.99 sq mi) of which 49.04 km (18.93 sq mi) is inland water. The population density is 30.78 inhabitants per square kilometre (79.7/sq mi).