England name three T20 debutants for first match of Australia series
Phil Salt captains the side in Southampton in the absence of injured skipper Jos Buttler.
The T20 series is followed by five one-day internationals against the same opposition, with England picking youthful squads after relinquishing their T20 and 50-over world titles over the past year.
Essex's Cox was the top-scorer for men's champions Oval Invincibles in this year's Hundred competition while Barbados-born Bethell impressed for Birmingham Phoenix.
Surrey all-rounder Overton, who has played one Test for England, will play as a batter only as he recovers from a back injury.
England team:
Phil Salt (capt, wk), Will Jacks, Jordan Cox, Liam Livingstone, Jacob Bethell, Sam Curran, Jamie Overton, Jofra Archer, Adil Rashid, Saqib Mahmood, Reece Topley