Vuolijoki is a former municipality in Finland. The municipality was consolidated with the city of Kajaani in the beginning of year 2007. Vuolijoki was located in the province of Oulu on the shores of Lake Oulujärvi, and was part of the Kainuu region. In 2004 the municipality had a population of 2,643 and covered an area of 895.20 km2 of which 203.05 km2 was water. The population density was 3.8 inhabitants per km2. The municipality was unilingually Finnish.