In 1989, he joined English club Everton F.C. before returning to Sweden and IFK Göteborg in 1990 with which he won five Swedish Championships. He then moved to Swiss club Lausanne Sports before rejoining his old club Djurgårdens IF in 2000, winning another Championship in 2002 before retiring.
Rehn, with Finnish parents, received a call-up for the Sweden national under-18 football team but was ineligible to play until 1984 when he acquired Swedish citizenship. In total, he made eight U18 appearances (one goal) and 17 U21 appearances (three goals).
After his retirement, he was then part of Djurgården's coaching staff before taking the job as manager of his other previous Swedish club IFK Göteborg for the 2007 season as a joint manager with Jonas Olsson. He left in 2010. Between 2011 and 2013, he was head coach for Jitex BK, and in 2014 he joined Kopparbergs/Göteborg FC as head coach.
^ abcFrantz, Alf; Glanell, Tomas; Persson, Gunnar, eds. (2008). Det svenska fotbollslandslaget 1908–2008 [The Swedish National Football Team 1908–2008] (in Swedish). Vällingby: CA Strömberg AB. ISBN91-86184-69-5.