Iisalmi Church and the administrative parish was founded in 1627 and the area consisted of the current size of the Upper-Savo area a total of 6089 km ². Following present-day municipalities belonged to the parish: Iisalmi, Kiuruvesi, Lapinlahti, Sonkajärvi, Vieremä and part of Pielavesi. Eight last decades of 1700s marked strong population growth in the Upper-Savo and elsewhere in the country which continued in 1800s. This meant that new parishes were founded and population of Iisalmi parish declined. First to secede was Pielavesi in 1811, second Lapinlahti in 1858 and third Kiuruvesi in 1862.
Non-chartered borough of Iisalmi
Non-chartered borough of Iisalmi was declared October 24 1860 by Senate of Finland. According to declaration of non-chartered borough and implementation plan governor of Kuopio Province Furuhjelm drafted order to surveyor of commission C.W. Fors. He according to order divided lands and executed surveying. This was used as basis for zoning of Iisalmi non-chartered borough. The provincial governor had also prepared a proposal for non-chartered borough statute which the Senate confirmed 16 October 1861. This statute consisted of two chapters, the first of which was building code and second function of non-chartered borough government and other matters.
From non-chartered borough to town
Development of non-chartered borough into town was the an intricate and lengthy road. Governor-General von Berg inspired by Petter Kumpulainen drew up the first declaration of town in September 1856, but the Senate of Finland did not approve it. It took atleast five tries before it was approved. Finally, state secretary W. von Daehn's proposed matter to Emperor Alexander III who ordered in Petergof 22 July1891 with his "gracious declaration," to convert Iisalmi into a town. At the same time Emperor confirmed foundation book, building and zoning plans. These documents were signed by state secretary von Daehn who sent them to the Senate of Finland 20 October 1891. Senate decided to approve those documents. Therefore 20 October 1891 is considered to be the day of foundation of Iisalmi town.
Rural municipality of Iisalmi
Rural municipal regulation was adopted in 1865. Rural municipality of Iisalmi started operations in 1874. This rural municipality consisted of Iisalmi, Sonkajärvi and Vieremä. Non-chartered borough of Iisalmi since its foundation was a separate municipality.
Common journey of Iisalmi, Sonkajärvi and Vieremä lasted until the time of independence. Sonkajärvi seceded in 1920 and Vieremä seceded in 1921. Independence of Sonkajärvi and Vieremä meant that now the rural municipality of Iisalmi was in it's final form.
According to the 1917 local government act municipal board was executive and administrative body of Iisalmi. This municipal board had to represent all of Iisalmi. Therefore in 1922 seven municipal board districts were created. Act of 1948 gave municipal government much more power and responsibility.
Development of municipalities led to merger of rural municipality of Iisalmi and Iisalmi town in the end of 1969. Thus the current Iisalmi town began operating in 1 January 1970.