Meredith was one of three flyhalves named in the squad along with Carter Gordon and Ben Donaldson. Meredith's ACT Brumbies teammate Tane Edmed was dropped after struggling for game time in Super Rugby.
The other uncapped players were locks Lachlan Shaw and Miles Amatosero but there was no place for in-form Queensland Reds second-rower Lukhan Salakaia-Loto.
Prop James Slipper, Australia's most capped player, was named despite having announced his retirement last year.
Overseas-based centre Len Ikitau, loose forward Tom Hooper as well as props Taniela Tupou and Angus Bell were included in the squad.
Rugby league convert Zac Lomas and flyhalf Tom Lynagh were listed as unavailable for selection along with former captain Will Skelton.
"There have been ongoing discussions amongst the coaches for a number of months and, as always, there are some very good players who have not been selected for this first international window," said Schmidt, who will stand down and make way for Les Kiss after the three tests.
Wallabies' Nations Championship squad
Forwards: Allan Alaalatoa, Miles Amatosero, Angus Bell, Charlie Cale, Josh Canham, Nick Champion De Crespigny, Tom Hooper, Fraser McReight, Josh Nasser, Zane Nonggorr, Brandon Paenga-Amosa, Billy Pollard, Aidan Ross, Lachlan Shaw, James Slipper, Carlo Tizzano, Taniela Tupou, Rob Valetini, Jeremy Williams, Harry Wilson.
Backs: Jock Campbell, Filipo Daugunu, Ben Donaldson, Josh Flook, Carter Gordon, Len Ikitau, Max Jorgensen, Ryan Lonergan, Tate McDermott, Declan Meredith, Hunter Paisami, Dylan Pietsch, Harry Potter, Joseph-Aukuso Suaalii, Kalani Thomas, Corey Toole, Tom Wright.