Kaarina (Finnish pronunciation: [ˈkɑːrinɑ]; Swedish: S:t Karins, i.e. "Saint Catherine's") is a town in Finland, located in the region of Southwest Finland. It lies south of the regional capital, Turku. The population of Kaarina is approximately 37,000, while the sub-region has a population of approximately 353,000. It is the 31st most populous municipality in Finland, and the second largest municipality in the Southwest Finland region after Turku.

Kaarina has an area of 179.58 square kilometres (69.34 sq mi) of which 29.15 km² (11.25 sq mi) is water. The population density is 243.28 inhabitants per square kilometre (630.1/sq mi).

The municipality is unilingual Finnish, with a Swedish minority and a Swedish comprehensive school. Bilingualism was proposed but rejected in 2015.

The famous artist Tom of Finland was born in Kaarina. Kaarina has a football team called Kaarinan Pojat. The Kino Piispanristi is the largest independent cinema in Southwest Finland.

The municipality of Kuusisto was merged with Kaarina in 1946. The municipality of Piikkiö was merged with Kaarina in 2009. At the same time, Kaarina adopted Piikkiö's coat of arms.

Results of the 2011 Finnish parliamentary election in Kaarina:

Kaarina is twinned with: