Uusikaupunki, is a town and municipality of Finland.
It is located in the Finland Proper region. The municipality has a population of 15,687 (30 September 2012) and covers an area of 551.65 square kilometres (212.99 sq mi) of which 49.04 km2 (18.93 sq mi) is inland water. The population density is 31.21 inhabitants per square kilometer (80.8 /sq mi).
The municipality is unilingual Finnish. Both its Finnish and Swedish names mean literally "new town".
Uusikaupunki is the home of Valmet Automotive, a contract automobile mechanical production company, producing cars and vehicles for other manufacturers.
In 1721, the Peace of Nystad was signed in Uusikaupunki, ending the Great Northern War between Sweden and Russia.
The original name of the main village that was incorporated into Uusikaupunki was Kalainen (which is a Finnish adjective meaning "having plenty of fish"). The village of Kalainen originated as a market place for the people of Vakka-Suomi. The town of Uusikaupunki was founded as a town with the rights of commerce in 1617 by decree by Gustav II Adolf.
Up to the 19th century it was an important port for commerce and fishing, and up to the latter half of the 20th century it still retained an important ship building industry.
Uusikaupunki is home of the Bonk