He earned his living nearly exclusively from music and at the age of 12, he gave a performance as a pianist at a concert of the Vienna Men's Choral Society.
Gustav Mahler premiered Braun's Marionettentreuse at the Vienna Court Opera on 17 October 1906, to excellent reviews.
In 1923 Arnold Schoenberg used his influence to obtain financial assistance for some struggling composers, including Braun, Alban Berg, Anton Webern and Josef Matthias Hauer.
Braun wrote seven works for the one-armed pianist Paul Wittgenstein, including a Piano Concerto in A minor for the Left Hand.
This concerto was written in 1924 and was first performed on 12 December 1927, almost two years after his death, with Wittgenstein as soloist and Julius Lehnert conducting.