Career
He was also part of Greece Under 21 team On 1 July 2009 Association for the Study of Internal Fixation Kavala announced the transfer of Siontis for an undisclosed fee. On 27 July 2011, he signed a 1-year contract with Panetolikos F.C.
On 23 August 2013 Veria announced the transfer of Siontis on a free transfer.
His contract is due to expire in June 30th, 2014. After Kerkyra"s relegation Siontis was released on a free transfer.
On 26 August 2015, Siontis returned to Veria as he signed a one year contract. Siontis debuted on 29 August 2015 for Veria in an away match against Panthrakikos, he played the entire match.