The Happy hitmaker has teamed up with the catwalk beauty to star in and provide the soundtrack for the seven-minute short called Reincarnation, which was directed by Chanel boss Karl Lagerfeld.
In a teaser clip, the model wears a Cinderella-style ballgown and dances with Williams, who is dressed in military uniform, as part of a dream sequence which tells the story of Gabrielle 'Coco' Chanel and her history with the fashion house's iconic jacket.
Williams, who is reportedly helping Delevingne launched her singing career, penned the track Cc the World and asked Lagerfeld if the model could collaborate on it.
Delevingne recalls the phone call she received from singer to Wwd.com, saying, "I was so happy (being asked), I think I screamed down the phone at him."
The full film will premiere on 1 December (14), ahead of the brand's Metiers d'Art fashion show in Salzburg, Austria.