Posušje is a town and municipality in Bosnia and Herzegovina. It is located in the West Herzegovina Canton, a federal unit of the Federation of Bosnia and Herzegovina.

The West Herzegovina Canton is one of the cantons of the Federation of Bosnia and Herzegovina. The West Herzegovina Canton is in the Herzegovina region in the southwest of Bosnia and Herzegovina. Its seat of government is in Široki Brijeg, while other municipalities within the Canton are Grude, Ljubuški and Posušje. It has 94,898 inhabitants, of whom more than 98% are ethnic Croats. Economically, it is the most developed part of Bosnia and Herzegovina.