Kaarina (S:t Karins 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 21,151 (2003) and covers an area of 60.59 kmē of which 0.89 kmē is water. The population density is 349 inhabitants per kmē.
The municipality is unilingually Finnish.