Trained as a cabinetmaker (1957), he attended Denmark’s Design School, graduating in 1960.
He then worked for Molibia and Hans J. Wegner before opening his own studio in 1963. He taught at Denmark’s Design School (1973–78) and was lector at the Royal Danish Academy’s Furniture School (1978–85). Bernt’s furniture designs were mainly in light wood such as ash and beech.
Some of his pieces have been used in theatres and concert halls in towns throughout Denmark. Petersen is recognized for his simple style which is suitable for industrial production. One of his finest pieces is a small, light stool (1959), in rosewood and cane, with beautifully shaped legs.