With an origin as a rock musician, Bjørnstad mentions the guitarist Bill Frisell as one of his inspirations, along with Norwegian drummers Audun Kleive and Per Oddvar Johansen.
Since 2000 he has collaborated with many bands and artists in a variety of genres. He has collaborated with artists like Bjørn Kjellemyr, Jon Eberson, Karl Seglem, and Ken Stringfellow. In 2013 he was playing with Hedvig Mollestad Trio, the Hilde Marie Kjersem Band, and Cakewalk. The debut album Shoot! of the Hedvig Mollestad Trio was recorded live in the studio with only a few minor overdubs.[2]