Mustonen started his career mainly as a longtrack rider and he reached the final of the
2014 Team Long Track World Championship, where Finland finished fourth just outside the medal placings. He continued to represent Finland and won a bronze medal the following year at the
2015 Team Long Track World Championship and despite top scoring for Finland in 2016 and 2017 they were placed outside the medals. Also in 2022, he became the national champion of Finland after winning the
Finnish Individual Speedway Championship. In 2023, he won a second national title, was part of the Finland team that competed at the
2023 Speedway World Cup in Poland and won a bronze medal at the
European Pairs championship. He represented Finland during the
2024 Speedway of Nations. == See also ==