[5] Because Ånge has few teams and his father was Zamboni driver at the local rink, Pettersson had opportunities for extra ice time in his youth.

[16][13] In the 2013–2014 season, when he was in grade eight, Pettersson began playing for the nearby Timrå IK's U15 squad because Ånge did not have a junior team.

[4][11] In his first two seasons with Timrå, Pettersson lived in Ånge and commuted about 100 kilometres (62 mi) to practice multiple times per week.

[11] As an elite player, it was considered unusual for Pettersson to join Timrå instead of a team in the Swedish Hockey League (SHL).

Unable to help Timrå IK gain promotion, Pettersson signed a three-year contract with the Växjö Lakers of the top tier SHL, on 6 April 2017.

[20] It was speculated the Canucks drafted Pettersson based partly on highly successful chemistry with Dahlén on the top line for Timrå IK, where they finished fifth and ninth in league scoring as teenagers.

[27] In the regular season and the playoffs combined, Pettersson scored 34 goals and 41 assists, for a total of 75 points in 57 games played.

Pettersson scored his first career goal against goaltender Mike Smith, and also recorded an assist in a 5–2 Canucks win.

[43] He notched his first NHL hat trick later that night in a 4–3 win over the Ottawa Senators, striking in the second and third periods before scoring the game-winning goal in overtime.

[44] Pettersson suffered a knee injury a night later when fellow rookie Jesperi Kotkaniemi appeared to hook him away from the play.

[45] In his first game back from injury on 21 January 2019, Pettersson scored a goal and recorded an assist in a 3–2 win against the Detroit Red Wings.

[52] On 30 December 2019, Pettersson was named to his second consecutive NHL All-Star Game to be played in a month, and was later joined by teammates Jacob Markstrom and Quinn Hughes.

Pettersson began the shortened 2020–21 season with the worst start of his career, posting just one goal and one assist in his first eight games, as the Canucks struggled out of the gate.

Despite being limited to just five games, due to a broken thumb,[64] Pettersson would go on to win a gold medal with Team Sweden at the 2018 IIHF World Championship.

[65] On 9 May 2019, Pettersson was included on the roster to return for a second successive tournament with Sweden at the 2019 World Championships held in Bratislava, Slovakia.

[66] On 7 August 2019, Pettersson was named the cover athlete for the Swedish edition of EA Sports' ice hockey video game NHL 20.