For the 1976 season, Grönhagen joined Djurgårdens IF Fotboll.[3] Over eight seasons, he played 146 league games for Djurgården and scored 48 goals.[4] In 1983, Grönhagen returned to GIF Sundsvall.[3] He finished his playing career in 1985.[3]
International career
He earned 18 international caps and scored four goals for Sweden.[5]
Managerial career
Grönhagen started his management career in GIF Sundsvall from 1986 to 89, before coaching IFK Sundsvall from 1990 to 92, Djurgårdens IF from 1994 to 96, GIF Sundsvall from 1999 to 2001.[3] In 2002, he took over IF Elfsborg.[3] He left Elfsborg after two seasons in 2003.[6]
In November 2003, it was announced that Grönhagen was to take over IF Brommapojkarna for the 2004 season.[7] He left after one season.[8] In September 2006, Grönhagen started his second tenure in Djurgårdens IF, taking over from Kjell Jonevret.[9] He managed the team for the remaining six matches of the season[10]