The World Game understands the 20-year-old, who spent two years with the Scottish giants, has joined the Reds on a 10-day trial.
Mazis recently has been on trial with both Central Coast Mariners and Western Sydney Wanderers.
The attacking midfielder is now in Adelaide and is eyeing a deal in the A-League for the 2020-21 season.
Canberra-born Mazis was signed by Celtic from the Belconnen Blue Devils in 2018 at the age of 17 after a successful trial.
He spent time with the Bhoys’ Under-20s and reserves, but was unable to eventually crack a first-team spot at the Scottish champions.
The Australian departed Glasgow in January this year and a month later signed with Italian club Triestina.
But with Italy engulfed by COVID-19 at that point, the number 10 exited the Serie C side in March for reported “personal reasons” and returned to Australia.
Adelaide have had eight players depart the club from last season with Riley McGree, George Blackwood and Lachlan Brook all heading to the UK, goalkeeper Paul Izzo moving to Greece and visa players Nikola Mileusnic, Kristian Opseth and Chen Yongbin all exiting.
The Reds have so far signed former Socceroo Tomi Juric, scholarship players Domenic Costanzo, Joe Gauci and Yaya Dukuly, midfielders Joe Caletti and George George Timotheou, along with Spaniard Javi Lopez and goalkeeper James Delianov.