Believed to be inspired by a passage from Fyodor Dostoyevsky's 1868–69 novel The Idiot, the film follows a donkey as he is given to various owners, most of whom treat him callously.

Noted for Bresson's ascetic directorial style and regarded as a work of profound emotional effect, it is frequently listed as one of the greatest films of all time.

They baptize the donkey, christening it Balthazar, along with Marie, Jacques's childhood sweetheart, whose father is the teacher at the small school next door.

Years pass until Balthazar is involved in an accident and runs off, eventually finding its way back to Marie, now a teenager.

The police send Balthazar to market, where a greedy local miller buys the donkey, exploiting it for pumping water and milling grain.

One rainy night, Marie, soaked and desperate, knocks on the miller's door, seeking shelter after running away from Gérard.

After making several prison-themed films using his theory of "pure cinematography", Bresson stated that he wanted to move onto a different style of filmmaking.

Bresson later confirmed that Marie was inspired by a character in Bernanos' novel, La Joie, and that Balthazar was meant to be based on the priest's death at the end of the novel.

Moreover, Bresson uses ideas and influences from Jansenism on the exploration of humanity, in which he compares the film's overall premise as following the life of Saint Ignatius.

[7] When Au hasard Balthazar first played in New York at the 1966 Film Festival, "it received mostly unfavorable notices".

[8] Andrew Sarris, one of cinema's most influential critics,[11] wrote in his 1970 review: "No film I have ever seen has come so close to convulsing my entire being ...

"[12][13] The New Yorker film critic Pauline Kael, however, wrote that although some consider the work a masterpiece, "others may find it painstakingly tedious and offensively holy".

"[15] The film's religious imagery, spiritual allegories and naturalistic, minimalist aesthetic style have since been widely praised by reviewers.

[16] In 2005, James Quandt referred to it as a "brief, elliptical tale about the life and death of a donkey" that has "exquisite renderings of pain and abasement" and "compendiums of cruelty" that tell a powerful spiritual message.

[10] In 2003, J. Hoberman stated, "Robert Bresson's heart-breaking and magnificent Au Hasard Balthazar (1966) – the story of a donkey's life and death in rural France – is the supreme masterpiece by one of the greatest of 20th-century filmmakers.

"[17] Manohla Dargis views Au hasard Balthazar as "one of the greatest films in history", writing that it "stirs the heart and soul as much as the mind.

The critics consensus reads, "Au Hasard Balthazar uses one animal's lifelong journey to trace a soberly compelling – and ultimately heartbreaking – outline of the human experience.

[23] Au hasard Balthazar is the inspiration for 1977 Tamil-language film Agraharathil Kazhutai directed by Indian director John Abraham.

The film was critically acclaimed upon its release and in 2013 and it was listed in IBN Live's 100 Greatest Indian movies of all time.

Other films inspired by Au hasard Balthazar include Todd Solondz's Wiener-Dog (2016) and Jerzy Skolimowski's EO (2022).

[26] It was also 21st in the directors' poll, receiving 18 votes from filmmakers including Nuri Bilge Ceylan and Béla Tarr.