Mynämäki (Swedish: Virmo) is a town and municipality in the region of Lounais-Suomi in Finland. It is located in the Southwest Finland region. Neighbouring municipalities are Aura, Eura, Laitila, Masku, Nousiainen, Pöytyä, Rusko, Taivassalo Turku and Vehmaa.
The municipality has a population of 7,749 (31 January 2019) and covers an area of 536.08 square kilometres (206.98 sq mi) of which 16.37 km2 (6.32 sq mi) is water. The population density is 14.91 inhabitants per square kilometre (38.6/sq mi). The municipality is unilingually Finnish.