First he should take over his father's inheritance. When his parents divorced, Rühmann was just 14 years old. His father then committed suicide. In 1919, after completing his schooling and completing his secondary school leaving certificate, Rühmann took acting lessons. He got his first theater role a year later in the play "Rose Bernd". Shortly afterwards, Rühmann played with Theo Lingen at the Residenztheater in Hanover. In 1923 Rühmann became a member of the Schauspielhaus Munich, from where he moved to the Munich Kammerspiele a year later. During this time he married the actress Maria Herbot. Rühmann got his major roles from 1927 in Berlin with Max Reinhardt. Among others, he played here with Marlene Dietrich and Hans Albers.

In 1930, Rühmann realized his dream and got his pilot's license. The famous film "The Three from the Gas Station" was also made during this time. The film, which was one of the first German sound films, made him the most popular actor in Germany. During the Second World War, Rühmann was indifferent to politics. He tried to come to terms with the rules of National Socialist cultural policy, which benefited his career. He was later blamed for his friendship with high-ranking members of the Nazi regime. In 1938 he divorced his wife. Shortly afterwards he married the actress Hertha Feiler, with whom he also had a son. From 1938 to 1945 Rühmann was a member of the Berlin State Theater under the direction of Gustav Gründgens. During the Second World War, Rühmann was drafted into the Wehrmacht as a pilot. The funny film "Quax, the Break Pilot" was made, which was specially commissioned from Ufa-Film in 1941 by Propaganda Minister Josef Goebbels to keep the people happy.

In 1944, Rühmann appeared in the legendary comedy "Die Feuerzangenbowle", one of the classics that was produced to calm the "home front" during the war years. The film became one of his most famous films. After the end of the war, Rühmann was "denazified" and a temporary ban on playing was lifted. He moved back to Munich with his family and founded his own film company "Comedia" here in 1947. But this didn't bring him any luck; he had several failures. It wasn't until the film "Don't Be Afraid of Big Animals" came out that things started to look up again financially. Rühmann became a respected actor in post-war German cinema. He also had great success with "The Captain of Köpenick" by Carl Zuckmayer, among others. In this film, Rühmann played a shoemaker who took advantage of the confusion of authority in the military hierarchy to put himself in the position of a captain. In the 1950s, successful entertainment films such as "When the Father and the Son", "Charley's Aunt" and "The Pauker" were made.

With the thriller "It Happened in Broad Daylight" he asserted himself in demanding roles. In 1957 Rühmann was awarded the German Film Critics' Prize. Over time, the comedian became a character actor. Rühmann made a film in Hollywood in 1965: "The Ship of Fools" alongside Vivien Leigh. "The Love Carousel" was also created in 1965 with Gert Fröbe and Curd Jürgens. In 1966 the actor received the Federal Cross of Merit and in 1972 the Federal Film Prize. In 1968 Rühmann got his first television role in the film "Death of a Salesman" by Arthur Miller. Two years later his wife died. On October 9, 1974, he married Hertha Droemer for the third time. After the film "Fondenes Fressen" was filmed, Rühmann withdrew from acting and only appeared occasionally on television.

During this time he wrote his autobiography "That was it". A final film was released in 1993: "Far away, so close" by Wim Wenders. In 1995 he was posthumously awarded the Golden Camera as "Greatest German Actor of the Century".

Heinz Rühmann died on October 3, 1994 at the age of 92 on Lake Starnberg.