Born in Helsinki, he performed both internationally and in his native country where he was a visiting soloist at the Finnish National Opera for many years.

He created the role of the Judge in the world premiere of Aulis Sallinen's The Horseman at the Savonlinna Opera Festival in 1975.

[2] Wallèn made his operatic debut as Colline in La bohème in 1973 as a soloist of the Finnish National Opera.

[1][2][3] He was also a soloist at the Savonlinna Opera Festival, where he performed the role of the Judge in the world premiere of Aulis Sallinen's The Horseman in 1975.

[2] When the new opera house in Helsinki was opened in 1992, he appeared as the Father in Sallinen's Kullervo,[6] which was premiered in Los Angeles.