Harjavalta is a town and municipality in Finland. It's located in the Satakunta region, 29 kilometres (18 mi) southeast of Pori. The town has a population of 6,703 and covers an area of 127.74 square kilometres (49.32 sq mi) of which 4.28 km2 (1.65 sq mi) is water. The population density is 54.28 inhabitants per square kilometre (140.6/sq mi).

Satakunta is a region of Finland, part of the former Western Finland Province. It borders the regions of Southwest Finland, Pirkanmaa, South Ostrobothnia and Ostrobothnia. The capital city of the region is Pori. The name of the region literally means hundred. The historical province of the same name was a larger area within Finland, covering modern Satakunta as well as much of Pirkanmaa.