Cullberg studied ballet under Kurt Jooss-Leeder and Lilian Karina and at The Royal Ballet, London (1952–1957). In 1960, Cullberg was appointed director and choreographer at the Stockholm City Theatre. Some of her choreographies were premiered at the Royal Opera in Stockholm.
Cullberg gained international recognition by founding the Cullberg Ballet in the 1960s. On her retiring in 1985, her son Mats Ek took over the ballet company. The Swedish Arts Grants Committee instituted the Cullberg scholarship in her honour, and she was awarded an honorary professorship at Stockholm University, where she had studied when she was young. She also received the French honour Commendeur des Arts et Lettres and the Italian honour Cavaliere Ufficiale.