The appearance of the novel was a highly anticipated event as Victor Hugo was considered one of France's foremost poets in the middle of the nineteenth century. The New York Times announced its forthcoming publication as early as April 1860. Hugo forbade his publishers from summarizing his story and refused to authorize the publication of excerpts in advance of publication. He instructed them to build on his earlier success and suggested this approach: "What Victor H. did for the Gothic world in Notre-Dame of Paris [The Hunchback of Notre Dame], he accomplishes for the modern world in Les Miserables". A massive advertising campaign preceded the release of the first two volumes of Les Misérables in Brussels on 30 or 31 March and in Paris on 3 April 1862. The remaining volumes appeared on 15 May 1862. Critical reactions were wide-ranging and often negative. Some critics found the subject matter immoral, others complained of its excessive sentimentality, and others were disquieted by its apparent sympathy with the revolutionaries. L. Gauthier wrote in Le Monde of 17 August 1862: "One cannot read without an unconquerable disgust all the details Monsieur Hugo gives regarding the successful planning of riots." The Goncourt brothers judged the novel artificial and disappointing. Flaubert found "neither truth nor greatness" in it. He complained that the characters were crude stereotypes who all "speak very well – but all in the same way". He deemed it an "infantile" effort and brought an end to Hugo's career like "the fall of a god". In a newspaper review, Charles Baudelaire praised Hugo's success in focusing public attention on social problems, though he believed that such propaganda was the opposite of art. In private he castigated it as "tasteless and inept" ("immonde et inepte").
The work was a commercial success and has been a popular book ever since it was published. While exiled in England shortly after its publication, Hugo telegraphed his English publishers a one-character query: "?". Hurst & Blackett replied: "!". Translated the same year it appeared into several foreign languages, including Italian, Greek, and Portuguese, it proved popular not only in France, but across Europe and abroad.