Sundelin played five seasons with Team Kuortane (2018–2023) in the Naisten Liiga (NSML; renamed Auroraliiga in 2024), the premier national women's ice hockey league in Finland.

[5][6] As a junior ice hockey player with the Finnish national under-18 team, Sundelin participated in the IIHF U18 Women's World Championships in 2019 and 2020, winning a bronze medal at the 2019 tournament.

She made her senior national team debut at the 2021 IIHF Women's World Championship, contributing an assist to Finland's bronze medal performance, and went on to win a bronze medal while representing Finland in the women's ice hockey tournament at the 2022 Winter Olympics in Beijing.

[7][8] Her first goal at a major international event was scored against Japan in the preliminary round of the 2022 IIHF Women's World Championship and was assisted by Kiira Yrjänen.

[9] Sundelin attended secondary school at Kuortaneen urheilulukio ('Kuortane Lukio and Sports Academy') in Kuortane, Finland.