Yurduseven has stated that Besiktas have agreed terms withe the 31-year-old and that he will be a Besiktas player next season.
Tosic confirmed he would be leaving Gençlerbirliği on Instagram.
“A big THANK YOU to GENÇLERBIRLIGi, club’s players and supporters for 3 wonderful years! “
Tosic turned down the opportunity to sign for Southampton according to TalkSport. The Serbia international was linked with a move to Southampton last summer but the move never materialised.
Trabzonspor were close to agreeing a deal with Tosic last month. The Black Sea Storm’s manager Ersun Yanal met with Tosic and his agent at the Calisto Restaurant in Büyükçekmece, Ankara but were unable to agree upon a deal.
The 30-year-old has made 30 appearances for the Ankara based side this season.