The state electorate of Wagin has an approximate area of 69,000 km².

It is comprised of 43 suburbs including Boddington, Boilup, Borden, Broomehill Village, Collanilling, Commodine, Contine, Dardadine, Dryandra, Dwarda, East Popanyinning, Glencoe, Gnowangerup, Gundaring, Hillside, Kukerin, Lake Grace, Lime Lake, Lol Gray, Lower Hotham, Malyalling, Marracoonda, Meeking, Moojebing and Murdong.

It is comprised of 152 localities including Amelup, Arthur River, Badgebup, Ballaying, Bannister, Beaufort River, Beenong, Bobalong, Bokal, Borderdale, Boscabel, Boundain, Bowelling, Boxwood Hill, Boyerine, Bremer Bay, Broomehill East, Broomehill West, Bullock Hills, Buniche, Cancanning, Carrolup, Cartmeticup, Changerup and Cherry Tree Pool plus parts of Fitzgerald River National Park.

It is comprised of the councils of Boddington, Broomehill-tambellup, Cranbrook, Cuballing, Dumbleyung, Gnowangerup, Katanning, Kent, Kojonup, Kulin, Lake Grace, Narrogin, Narrogin Shire, Pingelly, Shire Of Plantagenet, Wagin, Wandering, West Arthur, Wickepin, Williams and Woodanilling plus parts of Jerramungup.

It is surrounded by the state electorates of Albany, Central Wheatbelt, Collie-preston, Darling Range, Eyre, Murray-wellington and Warren-blackwood.

It is within the federal electorate of O'connor.