Born to a family from İskenderun, Köybaşı had begun to play football for İskenderunspor, a local club. Köybaşı started out as an attacking midfielder, but moved to left back after recommendations from his colleagues.[2] He briefly played for another local club, İskenderun Kartalspor, before joining Gaziantepspor in 2006.[2]
Gaziantepspor
Köybaşı began his professional career in the youth divisions of Gaziantepspor. On 6 May 2008, he signed his first professional contract. He featured in 24 matches with 21 starts during the 2008–09 season. At the end of the season, he was linked with the big four clubs of Turkey,[3] choosing Beşiktaş in the end.
Beşiktaş
Köybaşı joined Beşiktaş in June 2009 for a fee of €6.5 million, as well as an exchange of two Beşiktaş players.[4][5] He began playing with the team during pre-season friendlies, and made his competitive debut in a Super Cup match against Fenerbahçe on 2 August 2009.[6][7] In November 2009, he provided the assist to Rodrigo Tello's goal in a 1–0 victory at Old Trafford against Manchester Utd in the Champions League.[8] It was the first time since February 2005, spanning 23 games, that United had lost a group stage Champions League fixture at home.[citation needed] He scored his first league goal against Ankaragücü in December 2009.[2]
In September 2011, he provided two assists against Bursaspor, one from the free kick when Tomáš Sivok scored with his head in the 87th minute and the second with a cross to Filip Hološko who also scored with his head in the 90th minute securing the victory of 2–1 in an away game.
Fenerbahçe
On 14 July 2016, he signed a 3-year contract with the club.[9]
Köybaşı has featured for Turkey at U-21's level, where he gained five caps. Köybaşı was called up to the senior national team by Fatih Terim for a friendly match against Ukraine on 12 August 2009.[11][12] He won his first cap, replacing Arda Turan in the 86th minute.[13][14]