 Hamrén played in local team Ljusdals IF before starting his coaching career.Hamrén coached Norwegian team Rosenborg BK to league championship in his first full season with the club.His previous job was as manager of the Danish Superliga side Aalborg BK, where he guided the team to a 5th-place finish in the 2005–06 season, a 3rd place in the 2006–07 season, and to the championship in the 2007–08 season.