Fjelsted's art career began with critically lauded gallery works in the 1990s. After segueing into theater, commercial photography, and multiple disciplines for an FX company, in 2002 he wrote and directed animated short The Firefly Man (2003) which premiered at Telluride and sold to The Sundance Channel. Fjelsted moved to Los Angeles in 2003, and has since worked as a production designer for seventeen years. He has built character worlds for Netflix, HBO, Amazon, and Hulu, as well as for independent films premiering at Cannes, Sundance, Tribeca, and Berlin. In 2018, he won a Primetime Emmy and an Art Directors Guild Award for the production design of period comedy GLOW, and a second ADG Award in 2019. He was nominated again in 2020 for an Emmy and a third consecutive ADG Award.