Giorgos Giakoumakis was born on December 9, 1994 in Heraklion, Crete. He began his football career with his hometown club, POA, before making his professional debut with Platanias in 2012.

He played for Platanias for four seasons, making a total of 67 appearances, scoring 15 goals and providing five assists in all competitions.

In the summer of 2017, he was acquired by AEK, with whom he made 48 appearances, scoring three goals and providing two assists.

In 2020, after two loan spells at OFI (12 appearances, three goals, one assist) and Gornik Zabrze (12 appearances, three goals, one assist) in Poland, the Greek striker moved to the Netherlands for Venlo. There he had the best season of his career, scoring 29 goals and providing two assists in 33 appearances, winning the Eredivisie golden boot award for the 2020-21 season.

His performances attracted the interest of Celtic, who acquired him in August 2021. In Scotland, he continued with impressive consistency, counting 57 appearances, 26 goals and two assists, winning one league championship and two League Cups, while also becoming the top scorer in the 2021-22 season with 13 goals.

In February 2023, he moved to the United States with Atlanta United, where he managed to score 24 goals and contribute five assists in 43 appearances in the MLS and be voted Rookie of the Year for 2023.

In the 2024-25 season, the Greek striker played for Cruz Azul in Mexico, recording 40 appearances, nine goals and eight assists to his name, continuing his high performance on a new football continent.

At international level, Giakoumakis has made 22 appearances and scored four goals for the Greek national team, of which he has been a permanent member of the squad since 2020.