The 30-year-old Tunisian moves to Thessaloniki on the back of four years at St Andrew's where he made 84 appearances.
He was released by boss Alex McLeish at the end of last season's Championship promotion campaign.
He told the Birmingham Mail: "I am satisfied that my transfer to Aris has been completed.
"I know that I have arrived at one of the biggest teams in Greece and will try to give my all to help Aris achieve their objectives.
"I've heard about the passion of the supporters and I'm impatient to play for them."