Otso Mielonen was born in Oulu, Finland, and raised in Copenhagen, Denmark, where he is currently based. Throughout his musical journey, he has studied at Newpark Music Centre / Dublin City University under the guidance of Ronan Guilfoyle, Greg Felton, Matthew Jacobson, and Cormac O’Brien. After earning his BA in jazz performance, Mielonen pursued classical double bass studies with Erik Higgins in Aarhus, Denmark, alongside fellow bassist Kinnon Church. This encounter serendipitously led him to further studies at the Hogeschool voor de Kunsten Utrecht, where he studied historical bass under Joshua Cheatham. Currently (2024–2026), Mielonen is enrolled in the music education master’s program at the world-renowned Rhythmic Music Conservatory in Copenhagen.

Over the course of his career, Mielonen has had the opportunity to collaborate with a wide range of musicians and ensembles, including Sebastian Zawadzki, Jason Shooster, Anna Bignami, Chris Comhaill, Esbjerg Ensemblet, Ronan Perrett, and Simon Olderskog Albertsen.

Mielonen is also the founder of Decent Dreams, his primary artistic outlet and ongoing musical project. Rooted in a co-creational approach, Decent Dreams is inspired by the collective ethos of projects like Bon Iver and M-Base. The project centers on building a strong group sound where each individual voice can shine, fostering a space for collaborative creation and collective expression. With a fast-paced creative process and a punk-inspired aesthetic, Decent Dreams embodies Mielonen’s mission to make music that exists not only for the “me,” but for the “us.”

Additionally Mielonen is teaching ensemble and music theory classes at Københavns Kommunes Ungdomsskole, as well as double bass at Kulturskolerne i Høje-Taastrup.