From his extensive theatrical work, his role as "Mackie Messer" ("Mack the Knife") in the world premiere of Bertolt Brecht's "The Threepenny Opera" is particularly noteworthy. This performance took place on 31 August 1928 at the Theater am Schiffbauerdamm. At that time, Paulsen was considered a Brecht admirer. In 1938 Harald Paulsen became director of the Theater am Nollendorfplatz in Berlin, where mainly operettas were performed at that time. He also directed and performed in singing roles. He was forced to resign his position in 1945, following the End of World War II in Europe. Paulsen also appeared as an actor in over twenty silent films. His acting career continued into the sound film era and he appeared in approximately ninety sound films.