After finishing his studies clarinet with Walter Boeykens and piano with Robert Groslot at the Conservatory in Antwerp, Jaan Bossier founded the Mahler Chamber Orchestra. Since 1993, Bossier has been clarinetist for ChampdAction, where he made his conducting debut in December 2000. Since 2003, he has been playing the clarinet and the bass clarinet in the Lucerne Festival Orchestra. He is also founder and leader of the Jaan Bossier Quartet, for which he writes and arranges all the music.

Bossier has participated in conducting masterclasses with Jorma Panula and has taken private lessons from Pierre Boulez and Zsolt Nagy. He is the co-founder of Ensemble 306, a contemporary music ensemble based in Eindhoven, which he also conducted from 2010 until 2013. With soloists from the Mahler Chamber Orchestra and the WDR Symphony Orchestra in Cologne (DE), Bossier plays chamber music concerts in different European countries and in Japan.

From 2009 until 2015, Bossier has teached clarinet, bass clarinet and contemporary music at the Musikhochschule Bremen. Since 2014 he is a teacher at the IEMA (International Ensemble Modern Academy) at the Musikhochschule Frankfurt am Main