As a player, he represented Östers IF, AIK, Djurgårdens IF, Stabæk, KRC Genk, Helsingborgs IF, and Högabergs BK during a club career that spanned between 1988 and 2007.

His move to rival club Djurgårdens IF in 1996 was not a popular one amongst fans especially for a hooligan firm associated with AIK called Firman Boys.

After leaving the club Jansson received death threats and had his door painted orange (the color of Firman Boys) with the text Judas.

[3] Jansson earned one cap for the Sweden national team, making his only appearance in 1994 in a Joe Robbie Cup match against the United States.

Jansson denied wrongdoing, pointing to his years of experience and the fact that he has sold players for 50-60 million euros as evidence that he takes his jobs seriously.