Vilén first played hockey around the age of four in his hometown of Lahti, and played his youth and junior career with the Lahti Pelicans.[1] He plays defense because his older brother Elias made him do so in floor hockey matches.[2] Vilén made his professional debut with the Pelicans' SM-liiga club on 18 February 2020, at 16 years old. He recorded 15 minutes of ice time in the 3–0 loss to JYP Jyväskylä, a match he found out he'd be playing just one day prior.[3] In April 2020, he signed a two-year contract extension with the Pelicans.[4]
In the 2020–21 season, 17-year-old Vilén played 35 games in the SM-Liiga and six in the second-tier Mestis.[5] His first goal in the league came on 30 October 2020.[6] Following the conclusion of the season, he was drafted in the fifth round (129th overall) of the 2021 NHL Entry Draft by the New Jersey Devils. On 23 July 2021, he extended his contract with the Pelicans through 2023.[5]
Remaining in Finland for the 2021–22 season, his second full season of top-level men's pro hockey, Vilén played 50 games and averaged nearly 15 minutes of ice time, recording just six points and no goals.[7]
On 12 May 2022, Vilén was signed to a three-year, entry-level contract with New Jersey, but was loaned back to the Pelicans for the 2022–23 season.[8] Following the signing, Vilén stated that he was surprised and excited to be offered a contract so soon.[9] Following a run to the Liiga finals with Lahti, Vilén joined the Devils' American Hockey League (AHL) affiliate, the Utica Comets, making his AHL debut on 3 May 2023, in a playoff game against the Toronto Marlies.[2][10]
Following Devils training camp, Vilén was assigned to Utica for the 2023–24 season.[11] He recorded his first AHL point with two assists against the Syracuse Crunch on 27 October 2023.[12] On 24 November 2023, after missing three weeks with an injury, Vilén was assigned to the Adirondack Thunder, the ECHL affiliate of the Devils and Comets.[13][14] In his first weekend of ECHL play, he had an assist in each of two games against the Worcester Railers.[15][16] Shuffled up and down between the AHL and ECHL over the next few months, Vilén scored his first ECHL goal on 3 January 2024,[17] and his first AHL goal on 15 January, in a 5–4 overtime loss to the Syracuse Crunch.[18] Comets head coach Kevin Dineen praised Vilén's passing and skating in his first full year of North American play, and cited puck retrievals and applying pressure to puck carriers as areas where he initially struggled in adapting to the AHL. By the end of the year, according to Dineen, Vilén had become a "minutes-cruncher;" an integral part of the Comets' defense group.[19]
In the second period of a 30 September 2024 preseason game between the Devils and the New York Rangers, Vilén suffered an upper-body injury.[20] He was activated from injured reserve and assigned to Utica on 29 October.[21]
