Career
Iraklis
Giantsis started his career in the academies of the football team of his hometown. In 2003 he was spotted by Iraklis" scouters and he joined the football academy of Iraklis. On 1 July 2006, Giantsis signed a professional contract with Iraklis.
He was released by the club in the summer of 2010.
Association for the Study of Internal Fixation Kerkyra
In the summer transfer window Giantsis signed on a free transfer for Association for the Study of Internal Fixation Kerkyra in the Greek Superleague. He debuted for his new club in a 2–1 winning match against powerhouse AEK F.C. for the 1st matchday of the 2010–2011 season of the Greek Superleague.
Giantsis made 10 appearances for the Greek U-21 team He debuted in 1–1 draw against the Albanian U-21 team in Ruzhdi Bizhuta Stadium, Elbasan on 20 August 2008.
