[1] Kakko was born in Kemi, Finland and joined Sonata Arctica in 1996, after studying keyboards for two years and singing informally in local festivals.

He initially performed both the keyboards and the vocals, but after the release of the band's first album, decided to concentrate on singing with the joining of Mikko Härkin.

Kakko appears on stage with Tarja performing "Beauty and the Beast," on Nightwish's live DVD From Wishes to Eternity.

More recently, he has been involved with a project Northern Kings, in which he, along with Juha-Pekka Leppäluoto (Charon), Marko Hietala (Tarot, Nightwish) and Jarkko Ahola (Teräsbetoni) sings covers of classics from decades past.

In July 2015, it was announced that Kakko would replace Jukka Nevalainen as Nightwish's special guest at the 2015 edition of Rock in Rio.