Uusikaupunki (Nystad in Swedish) is a town and municipality of Finland.
It is located in the province of Western Finland and is part of the Finland Proper region. The municipality has a population of 16,405 (2003) and covers an area of 540.65 kmē of which 47.72 kmē is water. The population density is 33.3 inhabitants per kmē.
The municipality is unilingually Finnish.
Uusikaupunki is the home of Valmet Automotive, a mechanical production company, producing cars and vehicles for other manufacturers.
In 1721, the Peace of Nystad was signed in Uusikaupunki.
