 Upon graduation, Söderholm returned to HIFK and received Liiga Rookie of the Year honors in the 2002–03 season.In his second year in the league, Söderholm won the Pekka Rautakallio Award as the Defenceman of the Year.After his third season, in which he served as HIFK captain, he took up an offer from Switzerland and embarked on a two-year stint with SC Bern of the National League A (NLA) in 2005.