Jannis Kalmazidis was born on 16 June 1968 in Budapest. He began his first volleyball training as an athlete in Sweden under the direction of Anders Kristiansson, with whom he later worked when the first began his coaching career. He has participated in the Seoul Olympics in 1988 and has won 6 titles, including 5 as an athlete of Iraklis. He was an athlete of PAOK from 1994 to 1999. He was also a player in Orestiada, Esperos Byzantiou and Aris. He is a coach of Speedball Lebanon. He is married and has 2 children.
As a coach, he started his career in Iraklis in 2007 as a partner of Swede Anders Christensen, with whom he won the Super Cup and the Championship. They moved together to Olympiakos where they won the 2008-09 doubles. Kalmazidis took over Olympiacos himself when Kristiansson resigned in February 2010 leading the team to win the championship. In the summer he stayed in Olympiakos as the second behind the Italian technician Flavio Gulinelli, who resigned the new year of 2011, leading the team again to win the double. He was a federal coach of the National Women’s Team from 2012 to 2016. In the period 2016 – 2017 he conquered with PAOK men’s team the first double in the history of the club.