He takes part in anti-bullying campaigns, as he was bullied himself when he was child due to his small size.

[1] Petrounias' debut major international medal came when he competed at the 2011 European Championships in Berlin, at the age of 20.

At the 2013 Mediterranean Games he won gold on the apparatus ahead of İbrahim Çolak of Turkey and Javier Gómez Fuertes of Spain.

[3] In June he competed at the inaugural European Games where he won gold on rings ahead of Nikita Ignatyev and Çolak.

[5] At the 2016 Olympic Games Petrounias won the gold medal on rings ahead of Arthur Zanetti of Brazil and Denis Ablyazin of Russia.

[6] In April 2017, Petrounias competed at the 2017 European Championships at the Polyvalent Hall in Cluj-Napoca, Romania.

[7] Petrounias won the gold medal on rings at the 2018 European Championships in Glasgow despite a shoulder injury.

[12] At the 2023 European Championships Petrounias won bronze behind Adem Asil and Vahagn Davtyan.

He won bronze on rings behind Chinese athletes Liu Yang and Zou Jingyuan.