Career
2006 Kosmidis came fourth in both the European Junior Championship in 2006. He went onto compete at the, winning two medals: silver in the floor exercise and bronze on Vault. In 2009 he competed as a Senior at the European Championships in Milan winning a Bronze medal on Floor Exercise.
He went onto compete at the World Championships in Rotterdam where qualified to the Floor final in 1st place.
In 2011 he failed to qualify for the Floor Exercise final at the World Championships in Tokyo, coming in 10th place in the qualification round. He returned to compete at the World Championships in Antwerp in 2013 but once again did not qualify for any of the finals.
In 2014 he competed at the World Championships in Nanning, China. He placed 7th on Floor Exercise in qualifications with a score of 15.533 qualifying him to the Individual Floor Exercise Final.