He left home and travelled to several countries. He finally ended up in Paris and lived there from 1913 to August 1914, where he attended Maurice Denis' painting school during daytime and went to the Acadamie Julien in the evening in order to study drawing nude bodies. While hoping to find success in Paris, he would ocassionally sell his artworks to public or cartoon illustrations to newspapers to make ends meet.

"In Paris Lang had an experience that would change the course of his life. One Sunday, while strolling in Montparnasse, Lang's attention was drawn to a movie house which adjoined a terrace café. Here, he saw a short film about a peasant revolt in France. "I want to be a painter," he remembered, "and it thrilled me to see pictures in motion!" The cinematograpé fascinated the young artist."... When you painted a horse naturally it was static— with film you could make it move"

When Archduke Ferdinand was assassinated in June 1914, Lang began to grow sceptical of residing in Paris, despite his friends assuring him that no trouble would come his way due to his Austrian and partially Jewish origin. A month later, Jean Leon Jaurès was assassinated on July 31. Franz left Paris only few hours after the news. He returned to Viena on 5 August, 1914, and rented a studio to focus on his painting. However, he could not do much work after returning from Paris and he soon volunteered in World War I, where he was eventually promoted to officer rank. He was wounded several times during his stint with the military. In 1918, he was deemed unfit to serve on the front-line and got discharged.

Lang was offered a role in a play titled Der Hias. During one of the performances, a representative of Decla-Film noticed Lang and invited him to come to Berlin to work for the company.
Erich Pommer, the head of Decla-Film offered him a contract, which allowed him to direct his first film, Halbblut (English title: The Half Blood or The Half Breed), after writing scenarios and acting in some films, mainly under the direction of Otto Rippert and Joe May.
Lang also assisted Joe May in his eight-part adventure serial Die Herrin der Welt (English title: The Mistress of the World). For the film, studio-based indoor sets were used to create exotic places such as Africa, China and the mystical lost city of Ophir. Getting to work on such big-budget adventure films set in exotic locales, Lang possibly got accustomed to it and went on to make several films that involved imaginative world building later in his career- Die Nibelungen, Metropolis, Woman on the Moon, The Tiger of Eschanpur and The Indian Tomb, to name a few.

Halbblut is released on 3 April, 1919.
Lang claimed to have finished the shooting of this film within five days. Contemporary reviews of the film reveal that Lang shot the outdoor scenes of the film inside the studio— a practice he would follow in his forthcoming and more ambitious projects such as Destiny and Die Nibelungen— to exercise complete control over the atmospheric effects that he the auteur in the making wished to create. The script was appreciated for its "dramatic and flawless logic" and critics acknowledged the potential of the up and coming director who "shows taste, expert knowledge, and a rare instinct from tonal values that are so effective cinematically that success is automatically assured." However, no print of this film possibly survives and it is considered "lost".

The Spiders: The Golden Lake, the most significant work of Lang's career so far, was released in October, 1919. A second instalment was released the following year.The Spider was a two-part serial adventure film which displays the cumulation of several of Lang's influences: his interest in pulp novels of Karl May, serial films of Louis Feuillade dealing with criminals and the experience of working with director Joe May on the elaborate sets of his films. The film flaunts Lang's love of the mysterious and unusual elements that would regularly feature in the films he made throughout his career such as underground caves, futuristic technological equipments and the idea of fantastical mystique.
Impressed by Lang's directorial efforts, Erich Pommer offered him to direct The Cabinet of Dr. Caligari. However, in the wake of the success of the first part of The Spider, Lang was assigned to direct a second instalment and the Caligari film was assigned to Robert Wiene. Wiene's expressionist vision was starkly different from Lang's elaborate realism, so it is unknown how the film would have ended up under Lang's direction. However, Lang's vision was incorporated in the film as can be seen how it is bookended with sequences having elements of realism that Lang suggested Pommer include.

The Wandering Image (alternate title: Madonna in the Snow) is the only Lang film that dabbles in Catholism. It marks the beginning of one of the greatest cinematic collaborations in the history of cinema— between Fritz Lang and Thea von Harbou. Although Lang continued to dish out films of great quality after this productive collaboration ended, almost every Langian holds the belief that he was at his best while he was working alongside Thea von Harbou, the talented author and screenwriter who also became his wife.

Fritz Lang met Thea von Harbou, whom he married two years later, in 1920 during the preparation for the film adaptation of her novel titled The Indian Tomb which Lang was initially slated to direct. However, Joe May, who was more experienced in film direction than Lang at that time, ended up directing the film. Following this, von Harbou became the screenwriter for all of Lang's films from The Wandering Image (1920) through to The Testament of Dr. Mabuse (1933). The novel was subsequently adapted two more times in 1938 and 1959, under the direction of Richard Eichberg and Fritz Lang, respectively.
The three adaptations of von Harbou's novel, according to film historians Meenakshi Shedde and Vinzenz Hediger in their academic paper titled "Come On, Baby, Be My Tiger: Inventing India on the German Screen in Der Tiger von Eschnapur and Das indische Grabmal", note three important stages in the history of German cinema, namely the burgeoning Weimar cinema (1921 version, dir. Joe May), the Nazi entertainment apparatus (1938 version, dir. Richard Eichberg) and the struggling German post-war cinema (1959 version, dir. Fritz Lang).
Despite the grandeur of the elaborate set design and imaginative storytelling, the adaptations could not avoid exuding an Oriental bias laden with stereotypes such as the depiction of Indian characters by white actors wearing brownface, navigating the land of mysticism and improvident kings. More than an earnest depiction of India, the film at times serves as a European understanding of India in the contemporaneous times. The film stirred controversy upon its Indian release. In an article published in September 1938, in FilmIndia, India's first film trade paper, renowned writer and publisher Baburao Patel expressed his dissatisfaction with Richard Eichberg's version of the film, calling for an immediate ban.
The three adaptations of the novel are in line with the strong interest in Indian philosophy that shaped German literary and philosophical thought starting in the early nineteenth century. Renowned figures such as Arthur Schopenhauer, Johann Wolfgang von Goethe, and Indologist Max Müller were among the great admirers of ancient Indian literary texts. For them, India represented an idyllic land where harmonious coexistence between nature and people still thrived, offering spiritual nourishment to a soul that had withered in Europe. Prana, the production company behind F.W. Murnau's Nosferatu (1922), was named after the Hindu concept of the universal life force.

Both Fritz Lang and Thea von Harbou had a lifelong fascination with India. As soon as they finished working on Joe May's The Indian Tomb, they began writing the screenplay for another film inspired by an Indian folk tale titled Der müde Tod (English title: Destiny). The film, a meditation on the idea of death, was based on the story of Savitri. Thea von Harbou was not only influenced by Indian mythology but also actively supported the cause of Indians living in Germany. She married Ayi Tendulkar, a Gandhian who had previously served as a private secretary to Sardar Patel. She was undeniably a staunch nationalist, and Allied interrogation records document her acknowledged memberships and activities during the Nazi era. In her defence, she asserted that she had only joined the Nazi Party in 1941 to support Indian immigrants living in Germany and Indian prisoners of war, emphasizing that she never worked explicitly for the Party and refrained from attending Party meetings, ignoring multiple warnings. According to her account, her direct contributions to the government were limited to volunteer efforts, including welding, manufacturing hearing aids, and providing emergency medical care. Notably, she was awarded a medal of merit for rescuing individuals during two air raids.

The seeds of a science-fiction film were sown in Fritz Lang's mind as he witnessed the spectacle of New York City's skyline during his visit for the American premiere of Die Nibelungen in 1924. He found himself bedazzled when confronted with rows of skyscrapers and elevated roads. For his grand project titled Metropolis, he drew from New York's imposing architecture and adopted the vertical scale of the city's Art Deco buildings.
With a production cost exceeding 5 million marks and the involvement of over thirty-seven thousand extras, Metropolis eclipsed previous German film productions in scale and ambition. The film's eponymous city stretches high above ground and burrows deep below the earth, dividing its population into two classes. Workers reside in cramped underground spaces called City of the Workers and devote themselves to maintaining the city's immense machinery called M-Machine (Maschinenmensch). The privileged elite inhabit the Club of the Sons and live in luminous towers, enjoying leisure and social gatherings. Lang depicts this bifurcation not merely as a backdrop, but as the core of the city's operations and class relations.
The film appeared during the Weimar Republic, at a moment when Marxist social theory was widespread. The film was a critique of the industrial order, with clear references to social division and capital-labour dynamics. Despite initial accusations that Lang promoted communist ideas, the narrative grows more complex: technological marvels merge with social commentary; scenes in futuristic offices and laboratories transform Metropolis from political allegory into speculative fiction. H. G. Wells, however, lambasted the film for its depiction of the future. As a true science fiction author, he criticised Lang for not consulting sociologists and architects to provide a scientifically accurate account and instead presenting a rather pulpy rendition. Yet Lang's greatness lies in the fact that he was not driven by a documentary impulse to depict the future. The power of these images was rooted in art and for this reason, he turned to artists and sculptors to conjure his vision of the future, setting aside the language of science in favour of the language of art.

M can rightfully be seen as one of the earliest proto-noirs and has been acknowledged amongst the most influential works of world cinema. Infact, Billy Wilder found inspiration from this film when he was working on Double Indemnity, which was soon anointed as one of the progenitors of noir genre by French film critics.
M, originally titled The Murderer Among Us, is an intricate character study that paints a compelling portrait of a serial killer in shades of grey while serving as a biting criticism of a negligent society. The story concerns a serial killer who preys on children and presents an underworld society whose usual business is disrupted due to everyday raids carried out by the police to apprehend the killer on loose. Driven by police's continued failure & increasing losses in their business, the criminal bosses ultimately decide to take matters in their own hands and try to capture the killer all by themselves. What's interesting about the way the paranoia is presented is that there's no central protagonist to guide us through the chaos, no light to shine out through the darkness. M is noteworthy for its dark commentaries on Berlin city life in 1931, its prescient diagnosis of a sensationalizing, press-dependent public, and the problems of justice.

After the Nazis rose to power, Lang's film The Testament of Dr. Mabuse was banned by Joseph Goebbels, the Reich Minister of Propaganda, who feared its anti-Nazi undertones and the potential to inspire dissent. Despite this, Goebbels was impressed by Lang's previous works, particularly Metropolis, and summoned the director for a personal meeting. During their encounter, Goebbels revealed that Adolf Hitler himself had seen Metropolis and expressed his appreciation. Goebbels even offered Lang a prestigious position as the head of all German cinema affairs, intending to make him a leading figure in the Nazi propaganda machine.
Lang, acutely aware of his partial Jewish heritage and the shifting political environment, felt increasingly threatened. Although he outwardly thanked Goebbels for the honour, he resolved immediately to expatriate. That same evening, he made arrangements to leave Germany, ultimately traveling to Paris and then emigrating to the United States, where he would continue his influential filmmaking career.

After narrowly escaping persecution at the hands of the growing Nazi dominance in Europe, Fritz Lang moved to USA and made his first English film, Fury, about the consequences of mob mentality, lynching, and the anger that comes from extreme injustice. The film is extremely significant as it comes during a time when lynch mobs were still an open secret and a public stain on the American conscience.
The film is about a group of otherwise normal town folks who can suddenly gather into frenzied mobs that unleash murder and mayhem under the garb of justice, much like Lang's fellow countrymen in Germany. Lang manages to simultaneously use the courtroom drama format to critique this violent act through which America perpetuated oppression on its minorities and the growing Nazis incursion in Europe. He originally wanted to make this a story about a black man's victimization at the hands of a mob, but unfortunately, he was restricted by production censors at MGM.

The Woman in the Window was released in 1944. That year also saw the release of Billy Wilder's Double Indemnity, Otto Preminger's Laura, and Edward Dmytryk's Murder, My Sweet. These films, along with 1941's The Maltese Falcon, collectively mark the first significant wave of film noir in American cinema. French critics coined the term “film noir” after the Second World War, when they were able to view these Hollywood wartime films. They recognized a distinctive type of crime thriller, characterized by an expressionistic visual style and psychological themes such as anxiety, alienation, and paranoia.

Next year's Scarlet Street not only overlapped The Woman in the Window in terms of both starring Edward but indeed all across the board starring Joan and Duryea and was also photographed by cinematographer Milton Krausner. Both the films track the gradual moral deterioration of a man whose better nature loses to his worst instincts, who goes from being an upstanding man to becoming a criminal on the run.
Scarlet Street was a pivot point in independent film production. It came at a point in Lang's career when he had essentially unfettered creative autonomy to explore his dark visions without the interference from front-office lackeys. Lang himself along with Joan Bennett and screenwriter Dudley Nichols were co-owners of the independent production company called Diana Production Company, whose business operations were overseen by producer Walter Wanger.

The Big Heat stands among the most significant works of noir cinema and is widely regarded as Fritz Lang's strongest American film. It captures the atmosphere of corruption that had infiltrated the police and legal system in the early 1950s. Glenn Ford delivers a tense performance as a homicide detective whose investigation into a powerful crime syndicate turns into a deeply personal and vengeful crusade. Gloria Grahame appears as the gangster's companion, driven by her own desire for retribution. Lee Marvin features as a starkly corrupt second-in-command to the gangster.

The film illustrates a shift from the earlier period of Hollywood, when violence was suggested rather than shown, toward a style where brutality was presented more openly. It reflects Lang's enduring preoccupation with hatred, murder, and revenge.

Fritz Lang passed away on August 2, 1976, at the age of 85 from a stroke in his home in Beverly Hills. His death brought an end to a remarkable career that significantly shaped both German and American cinema. Lang was laid to rest at Forest Lawn Memorial Park in Hollywood Hills, where many notable figures from the entertainment world are also buried.