Shojaei has joined AEK until the end of the season for an undisclosed fee, with renewal option for another year.
The Iranian international midfielder parted company with Panionios by mutual consent in early December.
Shojaei, who started his playing career in Sanat Naft in 2002, has played in Osasuna for five seasons and scored eight goals in 101 matches for the Spanish team.
Shojaei has also made 70 appearance for Iran national football team and scored eight goals.