[3] Pettersen first played minor hockey for Manglerud Star and Lørenskog IK, often at age levels several years older than his own.

[4] He joined South Kent School of the United States Premier Hockey League in 2014.

[5] He signed a tender with Omaha Lancers of the United States Hockey League on 4 January 2016.

[7] Following his sophomore season, Pettersen concluded his collegiate career by signing a three-year, entry-level contact with the Calgary Flames on 27 April 2020.

He returned for the 2017 IIHF World U18 Championship Division I, and led the tournament in scoring with 12 points in 5 games.