During the 2014–15 season, Holmström recorded ten goals and ten assists in 44 games during the regular season. He was tied for second overall in the SHL among junior-aged players in scoring. Holmström helped Skellefteå AIK reach the SHL Finals, and led the league in postseason scoring with seven goals and 11 assists in 15 games, breaking the league record for playoff points by a junior player, previously held by Daniel and Henrik Sedin.[3] On June 15, 2015, the Detroit Red Wings signed Holmström to a three-year entry-level contract.[4]
During the 2016–17 season, Holmström recorded one goal and one assist in 16 games, while being limited by injury during the regular season. He recorded three goals and four assists in seven playoff games to lead his team in playoff scoring. On April 3, 2017, Holmström was reassigned to the Grand Rapids Griffins.[5] During the 2018–19 season, Holmström recorded 12 goals and 13 assists in 65 games for the Griffins.[6]
On April 30, 2019, Holmström returned to Sweden and signed a two-year contract with HV71 of the Swedish Hockey League (SHL).[7]