Fritz Gruenbaum was born in Brunn (Brno), Moravia in July 1880. He completed his studies through high school and in 1899 moved to Vienna to study law. He also became interested in studying literature, which he pursued at the same time. Following graduation, he decided to forego the practice of law. He chose instead, to work in the theatre. Gruenbaum began writing librettos for operetta in 1903. He took small roles in various theatres and theatre groups. By 1906, he had moved up to cabaret theatre and became the emcee at the Souterrain in Vienna. The theatre in Berlin also opened for him in several theatres under the direction of Rudolf Nelson. Nelson recognized Grüenbaum’s talent for cabaret work and in 1910, He appeared as emcee in Nelson’s ‘Chat Noir,’ in the ‘Hoelle’ and in the ‘Simpl’ theater, Vienna.
With the outbreak of World War I Gruenbaum volunteered for the army. He was promoted to the rank a 1st reserve lieutenant and received distinctions for his service. After the war, he returned to cabaret performance working in both Vienna and Berlin theatres, such as the Simpl and the Ronacher. He married Lilly Herzel in 1916 who became his partner in cabaret routines. From 1920-33, he worked as revue and cabaret author, also as emcee in cabarets, primarily in Berlin and Vienna, catering to an intellectual and literary clientele. He acted in films and became a scriptwriter. Gruenbaum collaborated with Paul Morgan and Karl Farkas, with whom he developed the double emcee format. For a while, he acted as manager of the ‘Simpl.’ In 1933, he settled in Vienna. Gruenbaum made many guest performances in various localities, including Prague. From 1934 until 1938 he was co-manager, with Karl Farkas, of the ‘Simpl.’ Following the occupation of Austria by Nazi Germany in May 1938, Gruenbaum and his wife attempted to escape across the border with Czechoslovakia. Their effort failed. The Nazis arrested him in Vienna and sent him to the concentration camp of Dachau. In September of the same year, they transferred him to Buchenwald. There, together with Paul Morgan and Hermann Leopoldi, he formed a cabaret group to help entertain the inmates.
In October 1940, he was sent back to Dachau where, according to some records, he supposedly died of “paralysis of the heart” on January 14, 1941.