Viitasaari, also known by its older name Viitasalo, was originally the name of the island located near to the main settlement area, but was later adopted as the name for the entire parish.
The first habitation of the Viitasaari area was by migrants from the Häme region to the west, although permanent settlement did not occur until the 1500's.
The bulk of the population during the initial settlement period were from Häme, but Finns from the Savo region later claimed the majority.
In terms of its government and parish allegiance, Viitasaari initially belonged to the mother parish of Rautalampi, but due to the parish’s vast size and the lengthy travelling distances this entailed, Viitasaari soon began to seek independence.
Separation was finally achieved in 1635. The newly created region of Viitasaari would later be further split into the separate districts of Kivijärvi, Pihtipudas, Konginkangas and Kannonkoski.
In recent years these municipalities have been re-united again through sub-regional co-operation and inter-municipal co-operation with the municipality of Pihtipudas. Viitasaari and Pihtipudas have combined their service production under the joint operating body Wiitaunioni.
1635 Viitasaari gains independence from its neighbouring municipalities
1739 The father of Finnish history-writing, Henrik Gabriel Porthan, is born in Viitasaari
1868 Local government is established
1882 Finland's first municipal health officer is stationed in Viitasaari
1905 Finland's first rural secondary school is founded in Viitasaari
1996 Viitasaari becomes a town
2005 The cooperative organisation Wiitaunioni is established together with the municipality of Pihtipudas.