He started his career at his local club ÍF Völsungur Húsavik, and moved to Stoke City in England as a teenager. Failing to grab a place on the first team, he returned to Iceland to play for KR. After the 2004 season he moved to SK Brann in Bergen, Norway. He showed acceptable defensive skills, but clear weaknesses in his passing game and general offensive play from his right back position.[citation needed] Before the 2006 season, Kristján was moved into the central defence, after both Ragnvald Soma and Paul Scharner were sold after the 2005 season.
Kristján showed great speed, being tested as the fastest Brann player in the 40 metre dash before the 2006 season. He is also considered to have great strength in the air, even though he is shorter than most players who play in his position.[citation needed] Kristján and his teammate Ólafur Örn Bjarnason started the season excellently and were nicknamed Ørneredet which means Eagle's nest (Örn/Ørn is the Norwegian and Icelandic word for eagle). After several years in Bergen including the 2007 season which ended at the top position in the Norwegian Premier League, his contract with Brann ended after the 2009 season.[1]
Kristján retired after 2014 season. However, he came out of his retirement in 2017 after his brother, Lárus Sigurðsson, took over as manager of Þór.[2]
Kristján made his debut for Iceland in 2003 and went on to earn 53 caps. On 9 February 2012 he announced his retirement from international football.[3]
