Lapinjärvi (Finnish pronunciation: [ˈlapinˌjærʋi]; Swedish: Lappträsk) is a municipality in Finland, located in the southern interior of the country.

Lapinjärvi is situated in the eastern part of the Uusimaa region.

Neighbouring municipalities are Iitti, Kouvola, Loviisa, Myrskylä and Orimattila.

Lapinjärvi is a bilingual municipality with Finnish and Swedish as its official languages.

Results of the 2011 Finnish parliamentary election in Lapinjärvi: Media related to Lapinjärvi at Wikimedia Commons This Southern Finland location article is a stub.