Andersson made his professional debut in his native Sweden, with his local team from youth Malmö Redhawks. He appeared in 38 games in the HockeyAllsvenskan for 11 points in the 2012–13 season.[1]
Andersson left Sweden and followed his family footsteps to North America by playing a major junior season with the Barrie Colts of the Ontario Hockey League (OHL) before he was selected by the Calgary Flames in the 2015 NHL Entry Draft. On 15 September 2015, Andersson was signed to a three-year, entry-level contract with the Flames.[2]
Andersson began his professional career during the 2016–17 season with the Stockton Heat of the American Hockey League (AHL), recording 22 points in 54 games. Andersson made his NHL debut on 8 April 2017, against the San Jose Sharks.[3] The 3–1 loss was the Flames' final game of the regular season.[4]
Andersson started the 2017–18 season with the Stockton Heat. He was called up to the NHL for the first time that season on 9 November 2017.[5] His call up did not last long and he was sent back down to the AHL on 13 November, after playing one game.[6] Andersson was selected as the sole representative of the Heat for the 2018 AHL All-Star Game.[7] He was called up to the NHL for the second time that season on 19 March 2018.[8]
Andersson participated in the Flames' 2018–19 training camp but was cut before the final roster was finalized.[9] His reassignment to the Heat was short lived, however, as following the Flames season opener, they placed Travis Hamonic on injured reserve and recalled Andersson to the NHL.[10]
During the 2019–20 season, having established himself amongst the Flames as a top-four pairing defenseman, on 8 January 2020, Andersson signed a six-year, $27.3 million contract extension with the Flames.[11]
^"Sharks beat Flames 3-1 in regular-season finale". ESPN. 8 April 2017. Retrieved 9 October 2023. ...D Rasmus Andersson made his debut for the Flames after being a healthy scratch for 14 straight games.
^Yanover, Ari (9 November 2018). "HOW SWEDE IT IS". NHL.com. Retrieved 4 April 2018.