Roos as a youth originally played with Hanhals IF and IF Troja-Ljungby before making his Swedish Hockey League debut in the 2018–19 season with Frölunda HC.
After two seasons in the HockeyAllsvenskan with BIK Karlskoga, leading the blueline in scoring with 28 points in 2020–21, Roos was signed to a two-year contract in returning to the SHL with Skellefteå AIK on 4 May 2021.
[5] He registered his first NHL point assisting on Jonathan Toews second period goal in a 4–3 overtime loss to the Minnesota Wild on 30 October.
[6] On 12 November, Roos scored his first NHL goal on goaltender Anthony Stolarz in the second period of a 3–2 victory over the Anaheim Ducks.
[7] He played in 15 games with the Blackhawks, scoring one goal and three points before he was assigned to Chicago's American Hockey League (AHL) affiliate, the Rockford IceHogs on 12 December.