Lange hails from the city of Tromsø and joined the club Fløya at the age of five. As a 17-year-old, he became top scorer in the Third Division (level four) with 33 goals in 22 matches, and then moved on to play for Tromsdalen in the First Division (2nd tier). Lange stayed with the club for three seasons, during which he experienced a relegation and a season in the Second Division (3rd tier).
During the summer of 1997, Lange was sold to Tromsø, which played in the Norwegian Premier League (1st tier).
Lange scored seven goals in 11 matches for Tromsø during his first season, and nearly experienced another relegation, but Tromsø survived after having to play qualification matches. Lange also debuted for the Norwegian under-20 football team
In 1998, Lange scored 20 goals in 26 matches, and was almost sold to Coventry City. Lange stayed at Tromsø, however, as he could not come to an agreement with Coventry on the contract details.
In 1999, Lange become top scorer of the Norwegian Premier League, scoring 23 goals.
Lange also made his debut for the Norway U21s that season. In 2000, Lange started as a player for Tromsø, but was sold to the Turkish side Trabzonspor in July. Lange only played 14 matches and scored seven goals in Turkey, before he was sold in April 2001 to Belgian side Club Brugge, the team where he played until 2006.
In 2004, Lange debuted for the Norwegian National Team, playing against Wales.
In February 2009, Lange signed for Hartlepool United on a contract until the end of the 2008-2009 season. On his third game for Hartlepool, his shoulder was popped out of place.
On 13 March 2009, Lange had surgery on his injured shoulder and will not return to training for at least six weeks. In September 2009 he signed for Kvik Halden (in the fourth tier of Norwegian football) until the remainder of the season, making four appearances (two league games and both play-off games).
As of March 2011 he"s working as a scout for his former employer, Club Brugge.