Kalmar FF

Jansson began his senior career at Kalmar FF, and played 11 games in the Allsvenskan in 1985, as the "Red brothers" finished second, just two points behind champions Malmö. He then featured 17 times in 1986, as the club slipped down the table and ended the season in the relegation zone. They suffered a second-successive relegation zone in 1987, and dropped out of Division 1 Södra, despite Jansson scoring three goals in 16 games.

Östers IF

Jansson moved back to the top-flight with Öster, and scored two goals in 20 league games in 1988 as the club was relegated into Division 1. New manager Hans Backe then led Östers to the Division 1 Södra title in 1989, with Jansson scoring 14 goals in 26 appearances. He then scored five goals in 22 games in 1990, as the team secured European football with a fourth-place finish. He then scored 13 goals in 31 appearances in 1991, and also scored a goal against Olympique Lyonnais in the UEFA Cup. He went on to score eight goals in 28 games in 1992, as Östers finished second in the league, seven points behind champions Norrköping.

IFK Norrköping

He moved on to league champions Norrköping, and scored eight goals in 23 games as they finished second in the league in 1993, some five points behind champions Göteborg. He played 19 games without finding the net in 1994, as Norrköping finished in fourth place. He featured 25 times in 1995, as they had to beat GAIS over two legs after finishing in the relegation play-off zone. He scored one goal in six games in 1996, as Norrköping finished in eighth place.

Port Vale

Port Vale manager John Rudge signed him permanently during the summer of 1997 for a £200,000 fee. He scored five goals in 32 league and two League Cup appearances in the 1997–98 season, the last two of which helped to secure a 4–0 win over Huddersfield Town at the Alfred McAlpine Stadium on the final day of the season – the victory kept the "Valiants" out of the relegation zone.^[2] Jansson said that "That’s the first time in my career that I haven’t been able to sleep before a game. In Sweden you play almost for fun, but here this is my work and it was important we stayed up."^[2] However, he featured just eight times in the 1998–99 season before being released by new manager Brian Horton in February.

Return to IFK Norrköping

Jansson returned to Sweden and to former club Norrkoping to make four appearances in 1999. He then played five games in 2000 and six games in 2001, before retiring from Nya Parken.

Club

International

Appearances and goals by national team and year^[5]