The 6 ft. 4 in. (192 cm.) centre-back is an experienced Greek international who was signed by Liverpool due to Sami Hyypia's move to Bayer Leverkusen and injuries to Martin Skrtel and Daniel Agger at the start of the 2009/10 season. Kyrgiakos was the only member of the Greek international side to play every minute of the qualifying campaign for Euro 2008. He missed the victorious Euro 2004 because of knee ligament injury, but featured in all of Greece's three games in the Euro 2008 finals. Unfortunately for Kyrgiakos Greece finished the tournament without a single point. Kyrgiakos made his breakthrough with Panathinaikos in the 2000/01 season. He played in 12 Champions League games as the Greek giants reached the quarter-finals in the 2001/02 season, but missed most of the club's double-winning 2003/04 season after suffering knee ligament damage he sustained in a collision with Rangers' goalkeeper Stefan Klos in the Champions League. Incidentally his next club turned out to be Rangers. Kyrgiakos signed a loan deal in January 2005 with a view to a permanent deal at the end of the season. He won the Scottish championship and the league cup, but tried to find a new club during the summer. In failure to do so he signed a one-year contract with Rangers that was not renewed at the end of the 2005/06 season after his performances were way-below par. Kyrgiakos played two years as a regular with Eintracht Frankfurt that finished fourteenth and ninth in the Bundesliga in his time there, before he returned to his homeland with AEK Athens. He intended to play out his career in Greece, but couldn't resist Rafa Benítez' tempting offer to join Liverpool. 

With Carragher, Agger and Skrtel above him in the pecking-order, it wasn't a major surprise that the big Greek only played in Liverpool's first team 21 times during the 2009/10 season. Although he started 18 matches, he was on the bench for 25. When he did play, however, he was a commanding and dominant defender, unafraid to put himself at risk of injury in his efforts to claim the ball. He even found time to cause a nuisance at the other end of the pitch when he gave his team the lead at Stoke in the middle of January. The only really negative point of his debut season at Liverpool was his sending-off in the Anfield derby with Everton in February after being voted as Liverpool's official "Player of the Month" by the club's fans in the previous month. Marouane Fellaini, who was seriously injured in the challenge, was himself guilty of going into it recklessly that could easily have resulted in serious injury for the Greek defender. Under neither Roy Hodgson nor Kenny Dalglish did the big Greek defender seriously threaten the normal central defensive partnership of Skrtel and Carragher. 'Soto' featured in just over half of the club's 54 competitive matches during the season but eleven of those came in the Europa League. A clumsy tackle in Braga conceded the penalty which ultimately despatched Liverpool from the competition and his lack of pace became agonisingly apparent. Kyrgiakos started only four matches under Dalglish but in June 2011 he was given a 12-month extension to his current contract. Only a couple of months later he signed a two-year deal with Wolfsburg, returning to the Bundesliga. He only took part in seven league games for Wolfsburg before being loaned out to Martin O'Neill's Sunderland on the last day of January 2012 where he featured in four first-team matches before his loan-spell ended.

The tall Greek defender only appeared twice in Wolfsburg's first team during the 2012/13 seasob. and after a short term stint with Sydney Olympic in 2014 in which he played just two games he retired from playing.

Rafa on Soto's performance against Bolton in January 2010. "What has Sotirios brought? Headers. He is strong and he likes the challenge. It is something that we needed and right now he is doing well. His attitude has been contagious. Kevin Davies is very strong and it is not easy to stop him in the air, so Sotirios did really well. He lost one tooth in the game and that shows how hard it can be."