 Onay entered Turkish League as the coach of Adanaspor at the age of 30.He worked in numerous teams for non-stop 21 years, which is record in Turkish football history as total of 462 matches.He coached successively Zonguldakspor, Beşiktaş, Bursaspor, Mersin İdmanyurdu, Ankaragücü, Kayserispor, Gençlerbirliği, Adana Demirspor alongside Konyaspor, Denizlispor when the teams were competing in Division 2.