His first role was Marcellus in Julius Caesar in Bromberg (today Bydgoszcz in Poland).
After the Nazis seized power in 1933, Rameau escaped through Switzerland, the Netherlands, Italy, and Great Britain to the United States.
During the Second World War, he made small appearances in over 20 Hollywood movies.
In the 1944 mystery-thriller Gaslight, Rameau played Maestro Guardi, Ingrid Bergman's Italian singing teacher, which was perhaps his most recognised role in Hollywood.
He made his last film appearance in Hollywood in 1949 and returned to Germany, where he worked as a stage actor.