Halonen began his collegiate career for Michigan Tech during the 2018–19 season, where he recorded 12 goals and nine assists in 35 games.

[1] During the 2019–20 season in his sophomore year, he recorded 12 goals and 10 assists in 39 games, and ranked fourth on the team with 22 points.

[7][8] On March 28, 2022, Halonen signed a two-year, entry-level contract with the New Jersey Devils beginning with the 2022–23 season.

He was assigned to the Utica Comets, the American Hockey League (AHL) affiliate of New Jersey, on an amateur tryout contract for the remainder of the 2021–22 season.

[12] The Devils recalled Halonen on February 23, 2024, after Nathan Bastian was placed on injured reserve,[13] and he made his NHL debut two days later, in a 4–1 loss to the Tampa Bay Lightning.