Němec’s career as a filmmaker started in the late 1950s when he attended FAMU, the most prestigious institution for film training in Czechoslovakia. At that time, Czechoslovakia was a communist state subservient to the USSR, and artistic and public expression was subject to censorship and government review. However, thanks largely to the failure of purely propagandist cinema in the early 1950s and the presence of important and powerful people such as Jan Procházka within the Czechoslovak film industry, the 1960s led to an internationally acknowledged creative surge in Czechoslovak film that became known as the Czech New Wave, in which Jan Němec played a part. For graduation, Němec adapted a short story by Arnošt Lustig based on the author’s experience of the Holocaust. Němec would return to Lustig’s writing to direct the influential film Diamonds of the Night (1964), also based on the Holocaust. That film follows the fate of two boys who escape from a train taking them to a concentration camp. It is noted for its dramatic subjectivization of the experience of the Holocaust using experimental techniques including flashbacks, simulated hallucinations, and an unusual double ending that leaves the viewer in doubt as to the fate of its protagonists. It was his first major success, and while it passed the censors’ reviews, it helped lay the foundation for the political movement that was coming. The film has since been called an aesthetic and technical milestone in the exploration of human experience under extreme conditions.

His best known work is A Report on the Party and the Guests (1966). Its plot revolves around a group of friends on a picnic who are invited to a bizarre banquet by a charismatic sadist, played by Ivan Vyskočil, who eventually bullies most of them into blind conformity and brutality while those who resist are hunted down. The film received a particularly bad reception from the authorities as Vyskočil in the film had a remarkable likeness to Lenin, though according to Peter Hames this was accidental. Moreover, the cast consisted of various dissident Czechoslovak intellectuals of the day, including Josef Škvorecký. The film was viewed as being so subversive to the Communist state that Antonín Novotný, the president, was said to “climb the walls” on viewing it and Němec’s arrest for subversion was considered. However, before the political fallout from this was able to take effect, he managed to have one more feature approved: Martyrs of Love (Mučedníci lásky, 1966). Perhaps in consideration of the previous troubles he had suffered, the film was completely apolitical, but nevertheless its surrealist lyrical style did not endear it to the authorities, and Jan Němec was forced to work outside the government-approved system, producing the film Mother and Son (Mutter und Sohn, 1967), which won an award at the Oberhausen Film Festival. His next important feature was a documentary, Oratorio for Prague, of the Soviet-led invasion of Prague in 1968 that ended the liberal Prague Spring. It received standing ovations in New York in the fall of 1968. The film was banned, but Němec’s footage would eventually be used by countless international news organizations as stock footage of the invasion. Philip Kaufman’s film adaptation of The Unbearable Lightness of Being (1988) used footage from the film; Němec also served as an advisor.

Jan Němec left Czechoslovakia after 1968, but upon his return he was not allowed to make films. He attempted to leave the country soon after but was not able to do so until 1974. He was given a warning by the government that “… if he came back, they would find some legal excuse to throw him in jail.” From 1974 to 1989, he traveled to Germany, Paris, Holland, Sweden, and the United States. He stayed in the United States for twelve years. Unable to work in traditional cinema, he was a pioneer in using video cameras to record weddings, including documenting the nuptials of the Swedish royal family. After the fall of communism in Czechoslovakia in 1989, he returned to his native country, where he had made several films, including Code Name Ruby (Jmeno kodu: Rubin, 1997) and Late Night Talks with Mother (Nočni hovory s matkou, 2000), which won the Golden Leopard at Locarno. He had been a professor at his alma mater, FAMU, since 1996. In 2014, he protested against the president of the Czech Republic Miloš Zeman by returning the medals given to him by the first president of the Czech Republic Vaclav Havel. Jan Němec died of an illness on 18 March 2016; he was 79.