Career
Vallas, a defender, started his career at Skoda Xanthi, and he was transferred to Olympiacos on July 2003. He played for Larissa on loan for one season, 2006–2007. He has returned to his very first team, Skoda Xanthi, on July 2007.
On 26 September 2014, he announced his decision to retire from professional football.
Vallas competed for the Greece Olympic team at the 2004 Summer Olympics. Olympiacos F.C.
Greek Super League: (2): 2004-2005, 2005-2006
Greek Cup: (2): 2004-2005, 2005-2006.
Runner-up 2003-2004
Larissa F.C.
Greek Cup: (1): 2006-2007.