The Shire of Plantagenet is located in the southern part of the Great Southern Region of Western Australia and is bordered by the Shires of Denmark, Manjimup, Cranbrook, Gnowangerup and the City of Albany.
Mount Barker, the Shire's commercial centre, lies in the middle of the Shire. It is easily accessible from Muir Highway from the south-west, Albany Highway from the north and south and Porongurup Road from the east. In addition to Mount Barker, the Shire includes the settlements of Kendenup, Narrikup, Rocky Gully and Porongurup.
The Shire of Plantagenet Administration Centre is located in Lowood Road Mount Barker, 359km south of Perth and 50km north of Albany on Albany Highway.