Turan has joined Basaksehir on a two-and-a-half-year loan deal from Barcelona.
"I am very excited by the idea of doing what I like to do most in the world. I have missed football a lot," Turan told reporters in Istanbul at his signing ceremony.
Basaksehir's chairman Goksel Gumusdag said Turan will, excluding bonuses, have a salary of 2 million euros until the end of this season and 4 million euros for next season, excluding bonuses.
Over the duration of the loan period, Barcelona has the right to sell the player to another club. Were he to be sold next year, Basaksehir would receive 20 percent of the sale price and the year after it would receive 25 percent, Gumusdag said.