In the first two years following its publication, over 70,000 hardback copies of The Kite Runner were sold along with 1,250,000 paperback copies. Though the book sold well in hardback, "Kite Runner's popularity didn't really begin to soar until  when the paperback edition came out, which is when book clubs began picking it up." It started appearing on best seller lists in September 2004 and became a number one New York Times best seller in March 2005, maintaining its place on the list for two years. By the publication of Khaled Hosseini's third novel in 2013, over seven million copies had been sold in the United States. The book received the South African Boeke Prize in 2004. It was voted the Reading Group Book of the Year for 2006 and 2007 and headed a list of 60 titles submitted by entrants to the Penguin/Orange Reading Group prize (UK).
Critically, the book was well-received, albeit controversial. Erika Milvy from Salon praised it as "beautifully written, startling and heart wrenching". Tony Sims from Wired Magazine wrote that the book "reveals the beauty and agony of a tormented nation as it tells the story of an improbable friendship between two boys from opposite ends of society, and of the troubled but enduring relationship between a father and a son". Amelia Hill of The Guardian opinionated, "The Kite Runner is the shattering first novel by Khaled Hosseini" that "is simultaneously devastating and inspiring." A similarly favorable review was printed in Publishers Weekly. Marketing director Melissa Mytinger remarked, "It's simply an excellent story. Much of it based in a world we don't know, a world we're barely beginning to know. Well-written, published at the 'right time' by an author who is both charming and thoughtful in his personal appearances for the book." Indian-American actor Aasif Mandvi agreed that the book was "amazing storytelling. ... It's about human beings. It's about redemption, and redemption is a powerful theme." First Lady Laura Bush commended the story as "really great". Said Tayeb Jawad, the 19th Afghan ambassador to the United States, publicly endorsed The Kite Runner, saying that the book would help the American public to better understand Afghan society and culture.
Edward Hower from The New York Times analyzed the portrayal of Afghanistan before and after the Taliban:
Hosseini's depiction of pre-revolutionary Afghanistan is rich in warmth and humor but also tense with the friction between the nation's different ethnic groups. Amir's father, or Baba, personifies all that is reckless, courageous and arrogant in his dominant Pashtun tribe ... The novel's canvas turns dark when Hosseini describes the suffering of his country under the tyranny of the Taliban, whom Amir encounters when he finally returns home, hoping to help Hassan and his family. The final third of the book is full of haunting images: a man, desperate to feed his children, trying to sell his artificial leg in the market; an adulterous couple stoned to death in a stadium during the halftime of a football match; a rouged young boy forced into prostitution, dancing the sort of steps once performed by an organ grinder's monkey.
Meghan O'Rouke, Slate Magazine's culture critic and advisory editor, ultimately found The Kite Runner mediocre, writing, "This is a novel simultaneously striving to deliver a large-scale informative portrait and to stage a small-scale redemptive drama, but its therapeutic allegory of recovery can only undermine its realist ambitions. People experience their lives against the backdrop of their culture, and while Hosseini wisely steers clear of merely exoticizing Afghanistan as a monolithically foreign place, he does so much work to make his novel emotionally accessible to the American reader that there is almost no room, in the end, for us to consider for long what might differentiate Afghans and Americans." Sarah Smith from The Guardian thought the novel started out well but began to falter towards the end. She felt that Hosseini was too focused on fully redeeming the protagonist in Part III and in doing so created too many unrealistic coincidences that allowed Amir the opportunity to undo his past wrongs.
The Kite Runner has been accused of 'hindering' Western understanding of the Talibans by portraying its members as representatives of various social and doctrinal evils that the Talibans and their supporters do not consider typical and which they feel portray Talibans in an unfavourable light. Examples of this would be: Assef's homosexuality, pedophilia, Nazism, drug abuse, and sadism, and the fact that he is an executioner. The American Library Association reported that The Kite Runner was one of its most-challenged books of 2008, with multiple attempts to remove it from libraries due to "offensive language, sexually explicit, and unsuited to age group." Afghan American readers were particularly hostile towards the depiction of Pashtuns as oppressors and Hazaras as the oppressed. Hosseini responded in an interview, "They never say I am speaking about things that are untrue. Their beef is, 'Why do you have to talk about these things and embarrass us? Don't you love your country?'"
The film generated more controversy through the 30-second rape scene, with threats made against the child actors, who originated from Afghanistan. Zakria Ebrahimi, the 12-year-old actor who portrayed Amir, had to be removed from school after his Hazara classmates threatened to kill him, and Paramount Pictures was eventually forced to relocate three of the children to the United Arab Emirates. Afghanistan's Ministry of Culture banned the film from distribution in cinemas or DVD stores, citing the possibility that the movie's ethnically charged rape scene could incite racial violence within Afghanistan.