Kannonkoski 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 1,469 (30 June 2015) and covers an area of 549.62 square kilometres (212.21 sq mi) of which 104.87 km (40.49 sq mi) is water. There are all together 81 lakes in Kannonkoski. Biggest lakes are Kivijärvi, Vuosjärvi and Kannonselkä.The population density is 3.3 inhabitants per square kilometre (8.5/sq mi).