Bjørn is a 1981 graduate of the Norwegian Naval Academy. He holds a Bachelor of Science (cand scient) in Oceanography from the University of Bergen. His shore duty assignments include Chief of Staff, Royal Norwegian Navy Fleet; Transformation Manager, Royal Norwegian Navy; Naval Attaché/Assistant Defence Attaché, Norwegian Embassy in Washington DC; Commander, Norwegian Frigate Service; Program Officer, NATO's Centre for Maritime Research and Experimentation; Operations Officer, Naval Headquarters. His operational tours include Commander, HNoMS Bergen; Executive Officer HNoMS Stavanger and warfare officer positions on multiple navy vessels.

Since 2018 he has worked as a consultant and is still president of the Norwegian Navy League (Sjømilitære Samfund).