Kyyjärvi is a municipality of Finland.

It is located in the province of Western Finland and is part of the Central Finland region. The municipality has a population of 1,371 (31 March 2016) and covers an area of 469.62 square kilometres (181.32 sq mi) of which 21.39 km (8.26 sq mi) is water. There are all together 46 lakes in Kyyjärvi. Biggest lakes in Kyyjärvi are Lake Kyyjärvi, Heinuanjärvi and Kirvesjärvi. The population density is 3.06 inhabitants per square kilometre (7.9/sq mi).