While playing the role of Arv in Masquerade, Malberg was noticed by the Danish actor Olaf Poulsen who brought him to Copenhagen.
He appeared in several more films during the silent era for the major Danish directors of the period: George Schnéevoigt, Emanuel Gregers, Holger-Madsen and Lau Lauritzen, Sr.
Then in 1930, Malberg performed the lead role in the first purely Danish sound film as the priest in the crime mystery Præsten i Vejlby.
[1] It was not until he was 80 years old that Malberg played his most memorable role—as the farm owner Morten Borgen in the classic Carl Th.
Malberg credited Dreyer with teaching him the art of film acting.When for so many years one stood on a large stage, a huge square, and shouted lines over the audience, one must learn to tone it down and find a quieter form in front of the camera.
Malberg also cowrote two stage plays: Bolettes Brudefærd (with Orla Bock) and Gamle Postgaard (with Axel Frische).