It is located in the province of Western Finland and is part of the Satakunta region. The municipality had a population of 3,408 (2003) and covered an area of 149.88 km² of which 0.22 km² is water. The population density was 22.7 inhabitants per km².
The municipality was unilingually Finnish.
Before the 2009 consolidation, Kiukainen was twinned with: