With Australia entering the match with an insurmountable 2-0 series lead, coach Ewen McKenzie has opted to give the 203cm, 140kg second-rower an opportunity in the starting side in his home state.
The 22-year-old's inclusion represents one of the two changes made to the starting XV, with Skelton's Waratahs teammate Wycliff Palu returning at No.8 after missing the second test in Melbourne with a minor ankle injury.
There are two changes to the bench, with Brumbies prop Scott Sio and Waratahs outside back Rob Horne getting their first opportunities in the match day-squad for 2014.
Horne comes in for Pat McCabe, who has suffered a nerve compression injury to his shoulder, making him unavailable for selection this week, while Sio replaces the Western Force's Pek Cowan on the bench.
Australia: Israel Folau, Adam Ashley-Cooper, Tevita Kuridrani, Matt Toomua, Nick Cummins, Bernard Foley, Nic White, Wycliff Palu, Michael Hooper (capt), Scott Fardy, Will Skelton, Rob Simmons, Sekope Kepu, Tatafu Polota-Nau, James Slipper. Reserves: Nathan Charles, Scott Sio, Laurie Weeks, James Horwill, Ben McCalman, Nick Phipps, Kurtley Beale, Rob Horne.
