Early career Konstantelias was nine years old when he joined the academy of Agia Paraskevi in his hometown
Volos. Initially, he trained with his peers, but he quickly got into the training of the older ones. In 2013 he moved to
Thessaloniki for
PAOK Academy where he gained valuable experiences in domestic and international tournaments and was twice named MVP. At first he played as a forward and then he moved to the center, but also to the sides.
PAOK In 2021, Konstantelias broke in to the PAOK's first team, as on 17 January he made his first appearance with the men's team in the
OFI vs PAOK game. Shortly before he turned 18 years old. In fact, he finished the season, playing in a total of three games. On 20 January 2022, Konstantelias signed a six months' contract with
Jupiler Pro League club
Eupen on loan from PAOK. On the same day, PAOK announced the extension of the contract with the young international until the summer of 2026. On 30 July 2025, Konstantelias signed a contract extension with PAOK following news that a deal had been agreed with
Bundesliga club
VfB Stuttgart subject to a medical. ==International career==