The 32-year-old player has joined the Greek giant until the end of the season, with the option to negotiate a further year.
Shojaei has been released from Panionios and AEK Spanish coach Manolo Jimenez considers him as an ideal replacement for captain Petros Mantalos, who has missed the remainder of 2017-18 season because of cruciate ligament injury.
Shojaei started his playing career with Sanat Naft Abadan in 2002 and has also played in Saipa, Al-Sharjah, CA Osasuna, UD Las Palmas, Al-Shahania Sports Club and Al-Gharafa Sports Club.