He is primarily known for the numerous operetta librettos that he wrote for composers such as Leo Fall, Jean Gilbert, Emmerich Kálmán, and Ralph Benatzky.

Schanzer was born into a Jewish family in Vienna where his father worked as a shipping agent.

He then began collaborating on operetta librettos with his friends and fellow writers Rudolf Bernauer and Ernst Welisch.

With the rise of Nazi Germany and the enactment of the antisemitic Nuremberg Laws in 1935, Schanzer left Berlin and moved to his villa in the Austrian spa town of Bad Ischl.

He returned to Vienna in 1936, but following the German annexation of Austria in 1938, he fled to Abbazia, a town now in Croatia but then under Italian control.