Färöischer Fußballpokal
Thorleifsson begun his professional career with Skála ÍF in 2002. Until 2006 he played in 68 matches and scored 7 goals with the club in the Faroe Islands Premier League. In November 2005 he transferred to B36 Tórshavn. Thorleifsson was in the starting line-up of B36 in the 2006 Faroe Islands Cup final, where his team won the trophy by winning 2–1 versus KÍ. Following reports about leaving B36, he moved to rivals HB Tórshavn in the summer of 2009.