Reinhold Schünzel was born November 7, 1888, in Hamburg. After finishing school, he completed an apprenticeship as a merchant in the Berlin-based publishing company Scherl. He then worked in Berlin, later in Hamburg, as a branch manager for the publishing company. Besides, Schünzel dabbled as an actor and director at several small theatres until he became a full-time actor in 1912. He then performed at Stadttheater Bern and at Berlin's Komödienhaus at Schiffbauerdamm and at Theater at Königgrätzer Straße.

With the help of a colleague, Schünzel landed his first movie role in 1916 in Carl Froelich's film "Werner Krafft". Still in the same year, he started his collaboration with director Richard Oswald who had a strong influence on the development of Schünzel's role image. Be it in Oswald's moral education films (including "Das Tagebuch einer Verlorenen" - "The Diary of a Lost Woman", 1918, "Anders als die Anderen" - "Different from the Others", 1918/19, "Das gelbe Haus / Die Prostitution" - "Prostitution", 1919), in his gothic movies and gangster films (including "Freitag, der 13.", 1916, "Unheimliche Geschichten" - "Tales of Horror", 1919), or in the crime films of the Max Landa series by E.A. Dupont and Carl Hagen – Schünzel played the self-indulgent bonvivant and seducer, the sly pander and extortionist. Schünzel starred in entertainment films just as in ambitious productions, for instance in Ernst Lubitsch's "Madame Dubarry" ("Passion", 1919) or in Carl Froelich's Schiller adaption "Luise Millerin" (1922), to name but a few.

In 1918, Schünzel made his debut as a director and adapted Friedrich Hebbel's play "Maria Magdalene" (1919/20) as well as the moral education film "Das Mädchen aus der Ackerstraße" and the elaborate history film "Katharina die Große". Still in 1920, Schünzel set up the production company Schünzel-Film and merged it several months later with the Vienna-based production company Micheluzzo & Co. (Micco-Film). The new production company then produced "Der Graf von Cagliostro" ("The Count of Cagliostro", 1920), starring Conrad Veidt and Anita Berber in the leading roles. Schünzel helmed the film as producer, director, and actor. For other productions, Schünzel also wrote the screenplay besides his other functions. This approach became typical for his movie work.

In May 1921, Schünzel became the assistant managing director and artistic director of the newly-found Berlin branch of Micco-Film and subsequently finished "Der Roman eines Dienstmädchens" (1921) and "Das Geld liegt auf der Straße" for Micco-Film. In May 1926, Schünzel again started his own business with his production company Reinhold Schünzel-Film GmbH. He produced a series of comedies, at first commissioned by UFA, and from 1928 on for Südfilm AG. Schünzel mostly was leading actor and director at the same time while displaying his full comedic potential in films such as "Hallo Cesar!" (1926), "Adam und Eva" (1928), "Don Juan in der Mädchenschule" (1928), "Aus dem Tagebuch eines Junggesellen" (1928), and others.

The start of the sound film era effectively ended Schünzel's work as a producer. Instead, Schünzel starred in more and more films of his colleagues, for instance, in Oswald's "1914. Die letzten Tage vor dem Weltbrand" ("1914: The Last Days Before the War", 1930/31) or in G.W. Pabst's "Die 3-Groschen-Oper" ("The Beggar"s Opera", 1930/31). From 1931 on, Schünzel worked as a director for UFA and finished a number of very successful musical films in the following years, including "Saison in Kairo" ("Cairo Season", 1933), "Viktor und Viktoria" ("Viktor and Viktoria", 1933), "Die englische Heirat" (1934), "Amphitryon" (1935), and "Land der Liebe" (1937), most often starring Renate Müller in the leading role. These films were all marked by an ironic undertone that eventually got Schünzel in trouble with the Nazi regime although he had been under Hitler's protection for a long time despite his Jewish belief.

In June of 1937, even before the premiere of "Land der Liebe", Schünzel left Germany for the United States, on an offer by Metro-Goldwyn-Mayer (MGM). But although the three musical films he finished for the studio over the next two years became quite successful ("Rich Man, Poor Girl", 1938, and "Balalaika", 1939) and featured stars like Joan Crawford and James Stewart ("The Ice Follies of 1939", 1938/39), Schünzel was not able to make his breakthrough in the United States. Thus, "New Wine" (1941) happened to be his last film as a director. Schünzel subsequently starred in several films, mostly in the mask of sinister Nazi villains, like "Hangmen Also Die!" (1942), "Notorious" (1946), and "Berlin Express" (1947/48).

In 1949, Schünzel returned to Germany and mainly worked as a theatre and movie actor. In the summer of 1954, he won the German film award as "Best supporting actor" for his role in "Meines Vaters Pferde". Shortly after, on September 11, 1954, Reinhold Schünzel died in Munich.