Kiukainen is a former municipality in the Satakunta region of western Finland. It was consolidated with the municipality of Eura on 1 January 2009, after which it ceased to exist as an independent administrative unit.
Before the merger, Kiukainen was one of the smaller municipalities of Satakunta, a region on Finland's west coast. Like other Finnish municipalities of its kind, it was responsible for local services such as schools, health care and municipal administration within its boundaries. Since 2009, the area of the former municipality has formed part of Eura.
Kiukainen is located in the inland part of Satakunta, in the south-western interior of Finland. The surrounding area is characterised by the flat, forested and agricultural landscape typical of the region, with numerous lakes and rivers nearby. The nearest larger centres include Eura and the town of Rauma on the coast.