 He began his football career in PAOK's youth system as a young boy and came through the ranks, winning titles at under-17 and under-20 levels.He made his first-team debut as a 17-year-old on 13 February 2014 in the Greek Cup quarter-final against Apollon Smyrnis.With his side already 4–0 up on aggregate, Koulouris replaced Stefanos Athanasiadis at half-time in the second leg and scored twice.