It is located in the province of Western Finland and is part of the Ostrobothnia region. The municipality consists of the central areas, the southern plain, and the extensive archipelago. Parts of the archipelago belong to the UNESCO World Heritage Site of Kvarken
One of Korsholm's more notable landmarks is that it holds Finland's longest bridge, the Replot Bridge. The bridge connects the island of Replot to the mainland. Finland's second oldest stone bridge that is still in use, can also be found in Korsholm, in the village of Toby
Major islands in the archipelago include Replot, Björkö, Köklot, Panike and the Valsörarna archipelago.
Along the coast, Korsholm extends to two river outlets: Kyrönjoki river flows into the Vassor bay of the Gulf of Bothnia, and the Laihianjoki river flows into Vanhankaupunginlahti, the bay on whose shore the city of Vaasa is located
