Voss studied art history at the Universities of Heidelberg and Berlin and received his doctorate in 1907 under Henry Thode on the old German Renaissance painter Wolf Huber.

From 1912 to 1921, Voss was head of the drawing collection of the Museum of Fine Arts in Leipzig and, from 1922 to 1935, curator and deputy director of the Kaiser-Friedrich-Museum in Berlin.

Voss was, both before and after his appointment to direct Hitler's Führermuseum, a major player in the Nazi system of confiscations and forced sales of Jewish artworks.

[7][8] Voss frequently did business with Hildebrand Gurlitt,[9] who procured art from Paris[10][11] and Erhard Göpel, who was also an official Linz buyer.

[13] According to Allied investigators, "VOSS' position in all this intrigue is the unenviable one of a professed lover of France who kept his hands clean by leaving the dirty work to others and not asking too many questions.

The Chamber did not notice the omission and considered that Voss was not concerned by the Law for Liberation from National Socialism and Militarism of March 5, 1946.

The Public Prosecutor of the Chamber of Appeal, who was aware that the US authorities held incriminating material about Voss, started a new case against him.

[24] However, the investigative reports into Voss' role in acquiring Nazi looted art were classified secret for more than fifty years after the war.

The families of Nazi officials and dealers in Nazi-looted art such as Hildebrand Gurlitt, Heinrich Hoffmann and Maria Almas-Dietrich submitted claims to looted artworks[26] and in many cases were successful.

[27] Responding to demand for transparency, the German Historical Museum published a Linz database in 2008 and republished it in 2021 in order to assist researchers in tracking Nazi-looted art.