The Ghanaian international joins the Turkish giants on a season-long loan from English club Swansea.
Dede Ayew rejoined Swansea from an unsuccessful stint at fellow Premiership side West Ham United in January.
Dede, who has been at Swansea with his younger brother Jordan Ayew, couldn’t help the Welsh-based side to avoid relegation from the Premiership last season.
Ayew, who is the son of legendary footballer Abedi Pele, started his career at French club Olympique Marseille and he has also played for Lorient. Fenerbahce will be his 5th club and his first for a club in Turkey.
He will wear the number 20 jersey