Von Rosen was born in Stockholm.[2] She was the daughter of the artist Count Reinhold von Rosen and Elisabeth Österyd, his first wife.[3] A year after her birth, the family moved into Åkerö Manor, a lakeside castle in Södermanland.[2] Von Rosen was educated at home by a governess and, later, attended a parish school.[2] In 1934, she and her sister moved to their grandparents' home in Stockholm so that they could attend Anna Ahlström's School for Girls.[2] While living with her grandmother, she took up ballet lessons with Vera Alexandrova.[2] Her grandmother paid for her lessons with Alexandrova and with Otto Thoresen.[2]
In 1984, she was given the Royal Medal of Merit Litteris et Artibus.[4] She also directed ballet plays outside of Scandinavia, in Monaco, the United States, the United Kingdom and Russia. She was the head of ballet at the Stora Teatern in Gothenburg between 1970 and 1976 and also of Malmöbaletten between 1980 and 1987.[5][6]
In 1950, von Rosen married editor Allan Fridericia (1921–1991). Soon after, they moved to Denmark. She died from natural causes on 7 September 2014 in Copenhagen. She was 90 years old.[7]