[4] Ayhan made his debut against FC Augsburg in a 4–1 win on 5 October 2013, coming on as a substitute for Ádám Szalai.

[12] On 28 January 2023, Galatasaray announced the official negotiations for the temporary transfer of Kaan Ayhan from Sassuolo till the end of the season.

[15] Following the season, it was announced that Galatasaray had triggered the buy option on Ayhan's loan deal at the cost of €2.8 million.

[17] He was called up by manager Fatih Terim for Turkey's friendly match against Russia on 31 August 2016, and subsequent World Cup 2018 qualifier against Croatia.

[18] Kaan Ayhan gave his debut for the Turkey national football team on 31 August 2016 in a friendly against Russia.