In 1946, he continued his training at the Sadler’s Wells Ballet School in London, starting his dance career shortly afterwards with Sadler’s Wells Ballet (now The Royal Ballet). As early as 1949, he decided to devote himself to choreography, creating some extremely successful ballets for Sadler's Wells Ballet, as well as for New York City Ballet, Ballet Rambert, Ballet de l’Opéra National de Paris and La Scala in Milan.
In 1961, he was appointed artistic director of the Stuttgart Ballet. He transformed this modest, regional group into one of the leading companies in the world, partly through his talent for discovering exceptional dancers. One of the most important of these dancers was Marcia Haydée, who was to become his muse.
Cranko’s big breakthrough in Stuttgart came with the world premiere of Romeo and Juliet (1962). He also created many smaller choreographic gems, such as Jeu de cartes and Opus I, but it was his dramatic narrative ballets like Onegin, The Taming of the Shrew, Carmen and Poème de l 'Extase that placed Cranko firmly in the pantheon of great choreographers. He successfully encouraged young dancers in his company – including Jiří Kylián and John Neumeier – to develop their choreographic talents.
He conquered the Metropolitan Opera in New York in 1969 with his gift for telling subtle stories with a clear structure. In 1973, John Cranko died unexpectedly. He left behind a unique repertoire that is still performed all over the world today.