Markopoulou was an active water polo player before transitioning to officiating. She became involved in refereeing after her playing career and rose through the ranks of the Greek water polo refereeing system alongside other female officials. Markopoulou has officiated in several national competitions in Greece and in international tournaments. She represented Greek refereeing at the World Cup competitions and made appearances in matches at World Championships. In 2024, she officiated matches at the
2024 Summer Olympics water polo tournament, including the women’s game between
Hungary and
Canada. ==Notable appointments==