On 25 February 2007, when he was playing against older young players in the season of Süper Gençler Ligi (Super Youth League) against Beşiktaş, in the fifth minute of the game, a kick from Batuhan Karadeniz collided with his head, forcing him to leave the game; he later went to a hospital to undergo head surgery (coagulation).

[2] After not receiving significant playing time, he joined fellow Süper Lig club Gaziantepspor on loan in January 2010 for the remainder of the season.

Kaya scored his first goal for the club against Samsunspor on 7 January 2012 in the 51st minute of a 2–0 comeback, with the game ending 4–2 for Galatasaray.

He continued to be first choice centre-back for the club and country, delivering calm and confident performances despite against top teams such as Manchester United and, internationally, against the Netherlands.

[8] On 14 July 2017, Kaya left Galatasaray and joined Czech club Sparta Prague, signing a three-year contract.

He made his debut for senior Turkish side on 29 February 2012, playing the entire game against Slovakia in a 2–1 loss.