Besiktas signed contract deals with four academy players, Oguzhan Akgun, Ridvan Yilmaz, Kartal Kayra Yilmaz and Ilkay Isler on Saturday at the club headquarters in Istanbul.
Seventeen-year-old Akgun and 18-year-old Yilmaz reached an agreement to extend their existing contracts to 2023.
Eighteen-year-old Yilmaz and Isler meanwhile signed three-year deals.
The four players were unveiled in an official signing ceremony alongside sporting director Ali Naibi who replaced Umut Guner earlier in the week.
Naibi was part of a reshuffle earlier in the week which club president Fikret Orman hopes will result in a more professional football department.
The commercial department of the club has been widely praised but has lacked synergy with the football department which has been criticized for the way it was run.
Besiktas have yet to make a transfer this summer since appointing Abdullah Avci as head coach.
The former Basaksehir manager replaced Senol Gunes who is now in charge of the Turkey national team.