Bruno started his conducting career at the Cologne Opera in 1894. Later that year he went to the Hamburg Opera to work as a chorus director. There he met and worked with Gustav Mahler, from whom he learned a lot. Mahler found him a job conducting at the opera house in Breslau. This is when he changed his name from Schlesinger (meaning: “someone from Silesia”) to “Walter”. He then went to Riga, returning to Berlin in 1900 where he conducted at the Staatsoper Unter den Linden where he worked with famous people such as Richard Strauss and Karl Muck.