On 9 May 2018, Bäck was signed to continue his development with BIK Karlskoga of the HockeyAllsvenskan for the duration of the 2018–19 season.[2] Receiving heavier minutes and responsibilities, Bäck registered 16 assists and 20 points in 45 regular season games. Following BIK Karlskoga's qualification series, Bäck returned to SHL club, Färjestad BK. On 7 April 2020, Bäck was re-signed to a one-year contract by Färjestad BK.[3]
On 21 April 2021, Bäck was signed by draft club, the Dallas Stars, to a three-year, entry-level contract.[4] After signing an NHL contract, Bäck spent the next three seasons in the American Hockey League (AHL) playing for the Texas Stars, Dallas' AHL affiliate.[5]
On 25 June 2024, the Stars re-signed Bäck to a one-year, two-way contract.[6] Bäck made his NHL debut on 10 October, in a 4–3 win over the Nashville Predators.[7] On 17 October, he recorded his first NHL point, an assist, in a 3–2 loss to the Washington Capitals.[8] On 14 November, Bäck scored his first NHL goal and added an assist in a 7–2 win against the Boston Bruins.[9]
