Australia open the new competition, which replaces the Tri-Nations with the addition of Argentina from this year, with a test against the world champion All Blacks in Sydney on Aug. 18.
Coach Robbie Deans named a 27-strong squad for a three-day training camp in Sydney next week but did not include any players from the Queensland Reds, who are still involved in the Super rugby playoffs.
Mitchell, who has scored 29 tries in 58 tests, and Turner, one of the quickest backs in international rugby, both missed the June tests against Scotland and Wales through injury.
Fullback Kurtley Beale and flanker David Pocock, who is likely to captain Australia in the absence of the injured James Horwill, were also included despite missing the end of the Super Rugby season with rib and groin injuries respectively.
James O'Connor, one of Australia's most dangerous attacking threats, remains a doubt for the Rugby Championship opener because of a hamstring problem and was not named, while experienced lock Nathan Sharpe has been rested.
Hard-running Western Force winger Nick Cummins, former Australia sevens captain Bernard Foley, outside back Mitch Inman and prop Paddy Ryan were among the uncapped players who will be pressing their cases at the camp.
Deans, who will name his final squad after a second camp in early August, said such gatherings were vital to expose as many players as possible to the national team's programme ahead of what will be a long international season.
"The camps provide us with an important opportunity for training background," he said in a news release.
"It gives us the chance to bring the whole group together and familiarise them with the method: 'tune' them in to Wallaby content if you like."
Squad: Kurtley Beale, Adam Ashley-Cooper, Drew Mitchell, Lachie Turner, Nick Cummins, Cooper Vuna, Rob Horne, Mitch Inman, Pat McCabe, Bernard Foley, Berrick Barnes, Nick Phipps, Nic White, Ben Mowen, David Pocock, Michael Hooper, Dave Dennis, Kane Douglas, Cadeyrn Neville, Hugh Pyle, Sitaleki Timani, Sekope Kepu, Benn Robinson, Ben Alexander, Paddy Ryan, Stephen Moore, Tatafu Polota-Nau.