Born in Athens, Kainourgios was playing at Sparti in Super League 2 before he earned a transfer to the Belgian top flight with Zulte Waregem, where he made 25 total league and cup appearances with two goals in the 2019/20 and 2020/21 seasons. From Zulte, Kainourgios moved on to Romanian club Dinamo București, but he would dissolve his contract before the end of the season prior to the club’s insolvency.
A player with a strong mentality to go with his size and speed at the left-back position, Kainourgios joined AKFC in August 2022.