Ivarsson won the overall world cup in orienteering in 1996. In 1998 he came second in the overall standings behind the Dane Chris Terkelsen . In 1995 and 1999 he won two bronze medals with the Swedish relay at world championships, and in 1997 also at the Nordic championships. At the Nordic Championships in Skellefteå in 1995 , he was third on the classic distance behind his compatriots Jörgen Mårtensson and Lars Holmquist and first in the relay. In 1998 and 2001 Ivarsson won the multi-day O-rings .
Ivarsson won 15 titles at Swedish championships. Ivarsson ran for the clubs IK Hakarpspojkarna , OK Illern , SOL Tranås and Bækkelagets SK . In 1992, 1999 and 2002 he won the Jukola relay race, 1995, 1997 and 2001 the Tiomila .
