Wim Jansen signed Larsson for Scottish club Celtic in July 1997 for a fee of £650,000. In his first season at the club, he played a crucial role in Celtic winning their first league title in ten years. He suffered a broken leg in a UEFA Cup tie against Lyon in 1999. Larsson came back stronger, scoring 53 goals in a 2000–01 season that saw him win the European Golden Shoe. Larsson won four league titles in his seven years at Celtic. He also helped the team reach the 2003 UEFA Cup Final against Porto, scoring both goals in a 3–2 defeat in extra time. His 242 goals in 315 matches saw Celtic fans nickname him "The King of Kings". Larsson joined Barcelona in 2004, where he won two league titles and the 2005–06 UEFA Champions League, providing the assists for both goals in the final. Following the expiration of his contract at Barcelona, Larsson returned to Helsingborg, although he also had a brief spell on loan at Manchester United in early 2007. He announced his retirement from football on 20 October 2009.