Beside her career as a movie actress she was also a busy operetta singer but also appeared in numerous theater plays, among others at the Rose-Theater in Berlin at the side of her second husband, the actor Hans Rose. This marriage also ended in divorce in 1944.
Loni Pyrmont's career began with small roles in Rudolf Nelson's operetta productions, after which she took part in cabaret performances in the Rhineland and Westphalia.
She belonged to the ensemble of the Berlin Rose Theater as Loni Rose-Pyrmont until the end of her stage career in 1944, and was also seen at the Theater in der Kommandantenstraße.
The actress and singer Loni Pyrmont got acting lessons at the Schauspielhaus Berlin before she entered the film business in 1919 with "Die Japanerin" (1919).
Loni Pyrmont made her best-known appearances in comedies, plays and operettas such as: Wenn man verliebt ist, Das Mädel von Davos, Der Raub der Sabinerinnen, Mein Leopold and Jean Gilbert's "Uschi".