He experienced the height of his film career in the 20s and he impersonated roles in the productions "Nachtgestalten" (1920), the title role in "Der kleine Muck" (1921) and "Der König und das kleine Mädchen" (1925).
After his film career he founded the jazz band "The Black Band", later he was also part of other bands like "William's Ragtime".
With the rise of the National Socialists he left Germany and he was working successfully as a musician abroad. Only at the end of the 40s he returned to Germany where he also made a contribution to the jazz in the FRG.
Both his father who came from Somalia and his mother who was from Germany were musicians and therefore Willi Allen grew up in an artistic impressed environment.