The 20-year-old winger joins from Istanbul Basaksehir for a fee of €13.4m, with a maximum of €1.5m in bonuses based on both Roma and Under’s achievements.
The winger has signed a five-year contract, trading the Turkish runners up for the second placed side in Italy, with his new club’s sporting director Monchi stating, “We are extremely happy with the arrival of Cengiz, a player with very important technical skills.”
The youngster enjoyed a breakthrough season in the Super Lig last time around, earning international recognition in the process.
Under scored 7 goals and registered 5 assists in 32 league appearances, with a direct hand in more goals as a result than any other player aged 21 or under in Turkey’s top-flight. He will hope for greater success than compatriot Salih Ucan, who spent two unproductive years on loan in the Italian capital.