Wales hand debut to Hathaway ahead of first Australia Test
Wales' miserable run, which includes a Six Nations wooden spoon, has seen them slide to 10th in the world.
"We've had a good week of preparations here in Sydney and are excited to get out on field on Saturday," said coach Warren Gatland.
"This first Test is going to be a great challenge for us. Test matches are all about fine margins and we know we need to be accurate, keep our discipline and stay in the fight for the full 80 minutes."
Gloucester's Hathaway will play alongside Rio Dyer on the other wing with 90-cap veteran Liam Williams moved to fullback.
Ellis Bevan, who won his first cap in the 41-13 defeat to South Africa two weeks ago, continues at scrum-half.
Thomas starts at flyhalf in his first appearance since 2021 despite playing most of his rugby at centre for Cardiff this year, while Mason Grady and Owen Watkin again pair up in the midfield.
Archie Griffin was selected at tighthead prop in his first senior start, with captain Dewi Lake at hooker and Gareth Thomas completing the front row.
Christ Tshiunza will feature for the first time since last year's Rugby World Cup 2023, partnering Dafydd Jenkins in the second row.
Taine Plumtree is at blindside flanker, Tommy Reffell at openside while Aaron Wainwright wins his 50th cap at No.8.
Gatland's men play two Tests against the Wallabies, in Sydney and Melbourne, as well as a fixture against the Queensland Reds in Brisbane.
Wing Keelan Giles, hooker Elliot Dee and flanker Jac Morgan are all out injured. Tighthead props Keiron Assiratti and Henry Thomas are also missing.
Wales (15-1)
Liam Williams; Josh Hathaway, Owen Watkin, Mason Grady, Rio Dyer; Ben Thomas, Ellis Bevan; Aaron Wainwright, Tommy Reffell, Taine Plumtree; Dafydd Jenkins, Christ Tshiunza; Archie Griffin, Dewi Lake (capt), Gareth Thomas
Replacements: Evan Lloyd, Kemsley Mathias, Harri O'Connor, Cory Hill, James Botham, Kieran Hardy, Sam Costelow, Nick Tompkins