Suomussalmi is a municipality in Finland and is located in the Kainuu region about 90 kilometres (56 mi) northeast of Kajaani, the capital of Kainuu and 120 kilometres (75 mi) south of Kuusamo. The municipality has a population of 7,172 (31 December 2023) and covers an area of 5,857.60 square kilometres (2,261.63 sq mi) of which 587.03 km2 (226.65 sq mi) is water. The population density is 1.36 inhabitants per square kilometre (3.5/sq mi). The municipality is unilingually Finnish. Ämmänsaari is the biggest built-up area in the municipality.

Kainuu, also historically known as Cajania, is one of the 19 regions of Finland. Kainuu borders the regions of North Ostrobothnia, North Savo and North Karelia. In the east, it also borders Russia.