Friedrich Zelnik, born May 17, in Chernivtsi, studied law in Vienna. From 1909 on, he worked as a theatre actor in Nuremberg, Aachen, Worms, Prague and Berlin. Then, in 1914, Zelnik started his career in the film business, initially as an actor. He soon became a star and started to make his own movies. In October 1915, Zelnik set up his own production company, Berliner Film-Manukfaktur, together with Walter Behrend and Max Liebenau, to produce the films he directed himself and films by other directors he starred in. His wife Lya Mara, an actress and dancer Zelnik met in Warsaw, became the female star of his movies.

Between 1917 and 1922, Berliner Film-Manufaktur produced more than 120 films. From 1920 on Zelnik's companies ran under several names: Zelnik-Mara-Film GmbH, Friedrich Zelnik-film GmbH, and Efzet-Film GmbH. In 1930, the Friedrich Zelnik-Film GmbH went into liquidation. In 1925, Zelnik was head of production at Deutsche Fox for six films, and in 1926 he became a board member and the art director of Defu (Deutsche Film Union AG) and Defina (Deutsche First National Pictures GmbH). Furthermore, Zelnik was the head of production at Deutsches Lichtspiel-Syndikat.

Despite his often expressed ambition that "movies have to accomplish a mission" (Urgiss, 1916), Zelnik became famous with numerous lowbrow films "that had been made as routinely and stalwartly as any popular entertainment novel" (Heinrich Fraenkel, 1956). Zelnik's sentimental costume dramas such as "An der schönen blauen Donau" ("The Beautiful Blue Danube"), "Die Försterchristel" ("The Bohemian Dancer"), "Das Tanzende Wien" ("Dancing Vienna"), "Heut" tanzt Mariett" – all of them starring Lya Mara and various male leads in regimentals, including Harry Liedtke, Wilhelm Dieterle, and Harry Halm – always ranked among the greatest box office hits of their respective season. Neverthless, his filmic version of Gerhart Hauptmann's "Die Weber" ("The Weaver") became popular even with "progressive" critics. To this day, this rather untypical film for Zelnik still mainly accounts for his reputation as a filmmaker.

In 1929/30, Zelnik's adaptation of Edgar Wallace's novel "Der rote Kreis" ("The Crimson Circle") was redubbed in London with music by Edmund Meisel. After visiting Hollywood in the middle of 1930, Zelnik without any problems adapted his operetta style to the sound film. Tellingly, his first sound film was a remake of his five-year old film "Die Försterchristel". In 1933, Zelnik went to London with Lya Mara and made "Happy", an English remake of "Es war einmal ein Musikus", the last film he did in Germany. In the following years, Zelnik worked as a director and producer. In 1938 and 1939, he finished two films in the Netherlands.

During the war, he became a British citizen and named himself Fred Zelnik. He then produced several films by other director in cooperation with British National. Again, he set up several production companies, for instance Victoria Films with Josef Janni in 1948, and then Fred Zelnik Films Ltd. Together with Raymond Stross, he founded Zelstro Films to produce the film "Hell Is Sold Out" but did not live to see its completion. Friedrich Zelnik died on November 29, 1950, in London.