Kimonas Kokorogiannis took Sotiris Leontiou in 2002 when he was playing for Panathinaikos. As a huge talent ηhe plays on loan from Panathinaikos in Marko and Proodeftiki. He returns to Panathinaikos and during the next the two seasons 2005-6 and 2006-7 he becomes a key member of the team. He participates in the UEFA’s Champions League qualification and Groups in his first season and in the Europa League the next one. The 2007-8 season starts in the worst way. A serious injury leaves him for a long time out of action. However, he returns strong and he plays on loan in Kavala and Ilioupolis. The 2012-2013 season Leontiou will play for Apollon Smirni, in which he will be crowned as the Football League Champion (Second National Division) and will win the promotion to Superleague. The season 2013-14 Fostiras acquire the player while the 2014-15 season he plays for Thesprotos. Leo is international with the National U19 and U21 Teams, in which he has 20 Matches.