An acclaimed literary work, The Elegance of the Hedgehog has been considered by critics and press alike as a publishing phenomenon. Upon the novel's release, it had received significant support from booksellers. The novel has earned Barbery the 2007 French Booksellers Prize, the 2007 Brive-la-Gaillarde Reader's Prize, and the Prix du Rotary International in France. The Elegance of the Hedgehog has been adapted into the film Le hérisson (2009).
The novel was a best-seller and long-seller in France, amassing sales of 1.2 million copies in hardback alone. It stayed on the country's best-seller for 102 straight weeks from its publication, longer than American novelist Dan Brown's best-selling books. According to reviewer Viv Groskop, the philosophical element in the novel partly explains its appeal in France, where philosophy remains a compulsory subject. Anderson agreed, commenting that the novel became popular in France because it is "a story where people manage to transcend their class barriers". The novel also received a warm response in Korea, and sold over 400,000 copies in Italy. The release of the novel helped increase the sales of Barbery's first novel, Une Gourmandise.
A week after the novel was published in the United Kingdom, The Guardian ran an article about French best-sellers published in English, focusing on The Elegance of the Hedgehog. In it, writer Alison Flood contended that "fiction in translation is not an easy sell to Brits, and French fiction is perhaps the hardest sell of all". Promotions buyer Jonathan Ruppin predicted that the novel would struggle to gain a readership in the United Kingdom because, according to him, in the UK market "the plot is what people want more than anything else" and the novel's storyline is not its central aspect.
The Elegance of the Hedgehog was well received by critics. In the earliest known review, for the Italian newspaper La Repubblica, Maurizio Bono writes that "[t]he formula that made more than half a million readers in France fall in love with [The Elegance of the Hedgehog] has, among other ingredients: intelligent humor, fine sentiments, an excellent literary and philosophical backdrop, taste that is sophisticated but substantial". French magazine Elle reviewer Natalie Aspesi pronounced it one of "the most exhilarating and extraordinary novels in recent years". Aspesi, however, tagged the novel's title as "most curious and least appealing". Praising the novel in his review for The Guardian, Ian Samson wrote that "The Elegance of the Hedgehog aspires to be great and pretends to philosophy: it is, at least, charming." In an earlier review in the same paper, Groskop opined that the novel is a "profound but accessible book ... which elegantly treads the line between literary and commercial fiction". She added that "clever, informative and moving, it is essentially a crash course in philosophy interwoven with a platonic love story". A review in The Telegraph conjectured that "[i]f [the novel were] a piece of furniture, it would be an Ikea bestseller: popular, but not likely to be passed down the generations". A review in The Times Literary Supplement went further, calling the book "pretentious and cynical, with barely any story. It reads more like a tract than a novel, but lacks even a tract’s certainty of purpose. The characters are problematic: most are puppets, and those that aren’t are stereotypes".
Michael Dirda of The Washington Post complimented Barbery, saying, "Certainly, the intelligent Muriel Barbery has served readers well by giving us the gently satirical, exceptionally winning and inevitably bittersweet Elegance of the Hedgehog." Louise McCready of The New York Observer praised Anderson's translation of the novel as "smooth and accurate". Caryn James of The New York Times hailed the novel as "studied yet appealing commercial hit", adding that it "belongs to a distinct subgenre: the accessible book that flatters readers with its intellectual veneer". Los Angeles Times ' Susan Salter Reynolds wrote that "[The Elegance of the Hedgehog] is a high-wire performance; its characters teeter on the surreal edge of normalcy. Their efforts to conceal their true natures, the pressures of the solitary mind, make the book hum".