In 2805, Earth is covered in garbage due to decades of mass consumerism facilitated by the megacorporation Buy 'n' Large (BnL). In 2105, BnL evacuates Earth's population in fully automated starliners, leaving behind WALL-E trash compactor robots to clean the planet. Eventually BnL abandons its plan and shuts down the WALL-E robots, except for one which develops sentience after 700 years of life-experience. He manages to remain active by repairing himself using parts from other units. Apart from his regular duties, he inquisitively collects artifacts of human civilization and keeps them in his home, a storage truck.
One day WALL-E discovers a growing seedling. Later, a spaceship lands and deploys EVE, an advanced robot probe sent from the BnL starliner Axiom to search for vegetation on Earth. WALL-E falls in love with the initially cold and hostile EVE, who gradually softens and befriends him. When WALL-E brings EVE to his home and shows her his collection, she sees the plant, automatically stores it inside herself, and goes into standby mode waiting for her ship to retrieve her. WALL-E, not understanding why EVE seems to have shut down, tries numerous methods to reactivate her, to no avail. When EVE's automated ship returns and collects EVE, WALL-E clings to its hull and thus travels through space to the Axiom, which is hidden behind a nebula.
On the Axiom, the descendants of the ship's original passengers have become morbidly obese after centuries of relying on the ship's automated systems for their every need. The ship's 6th captain, McCrea, leaves most of the ship's operations under the control of its robotic autopilot, Auto.
WALL-E follows EVE to the bridge of the Axiom, where the Captain learns that by putting the plant in the ship's holo-detector to verify Earth's habitability, the Axiom will make a hyperjump back to Earth so the passengers can recolonize it. However, Auto orders McCrea's robotic assistant GO-4 to steal the plant as part of his own no return directive, which was issued to all BnL autopilots after the corporation incorrectly concluded in 2110 that the planet could not be saved.
With the plant missing, EVE is considered defective and taken to the repair ward along with WALL-E (for cleaning). WALL-E mistakes the process on EVE for torture and tries to save her, accidentally releasing a horde of malfunctioning robots that were being kept for repairs into a robot's jail. The on-board security systems then designate both WALL-E and EVE as "rogue robots". Angry with WALL-E's disruptions, EVE brings him to the escape pod bay to send him home. There they witness GO-4 dispose of the missing plant by placing it inside a pod which is set to "self-destruct mode". WALL-E enters the escape pod in an attempt to retrieve the plant, but GO-4 jettisons the pod into space. WALL-E escapes with the plant before the pod explodes. Reconciling with EVE, they celebrate with a dance in space outside the Axiom.
With the plant brought to the captain, EVE's recordings of Earth are surveyed and concludes that mankind must return to restore their ruined home. However, Auto reveals his directive and stages a mutiny. He tasers WALL-E, severely damaging him, when he tries to protect the plant. EVE realizes the only parts for repairing WALL-E are in his truck back on Earth. She helps him bring the plant to the holo-detector to activate the ship's hyperjump. McCrea opens the holo-detector and fights Auto for control of the ship. Auto partially crushes WALL-E by closing the holo-detector on him. Auto is eventually disabled by McCrea, and EVE places the plant in the holo-detector, which frees a crushed WALL-E and sets the Axiom on the instant hyperjump to Earth.
EVE immediately brings WALL-E back to his home where she repairs and reactivates him. After the repair WALL-E no longer recognizes EVE, reverting to his original programming as an emotionless waste compactor. Heartbroken, EVE gives WALL-E a farewell kiss that jolts WALL-E's memory, and his personality returns. WALL-E and EVE happily reunite as the humans and robots of the Axiom begin to restore Earth and its environment.
WALL-E was met with critical acclaim. Rotten Tomatoes reported that 96% of critics gave the film positive reviews, based upon a sample of 236 reviews, with an average rating of 8.5/10. At Metacritic, which assigns a normalized rating out of 100 to reviews from mainstream critics, the film has received an average score of 94, based on 39 reviews, which represents "universal acclaim". indieWire named WALL-E the third best film of the year, based on their annual survey of 100 film critics, while Movie City News shows that WALL-E appeared in 162 different top ten lists, out of 286 different critics lists surveyed, the most mentions on a top ten list of any film released in 2008.
Richard Corliss of Time named WALL-E as his favorite film of 2008 (and later of the decade), noting the film succeeded in "connect[ing] with a huge audience" despite the main characters' lack of speech and "emotional signifiers like a mouth, eyebrows, shoulders [and] elbows". It "evoke[d] the splendor of the movie past" and he also compared WALL-E and EVE's relationship to the chemistry of Spencer Tracy and Katharine Hepburn. Other critics who named WALL-E as their favorite film of 2008 included Tom Charity of CNN, Michael Phillips of the Chicago Tribune, Lisa Schwarzbaum of Entertainment Weekly, A. O. Scott of The New York Times, Christopher Orr of The New Republic, Ty Burr and Wesley Morris of The Boston Globe, Joe Morgenstern of The Wall Street Journal, and Anthony Lane of The New Yorker.
Todd McCarthy of Variety called the film "Pixar's ninth consecutive wonder", saying it was imaginative yet straightforward. He said it pushed the boundaries of animation by balancing esoteric ideas with more immediately accessible ones, and that the main difference between the film and other science fiction projects rooted in an apocalypse was its optimism. Kirk Honeycutt of The Hollywood Reporter declared that WALL-E surpassed the achievements of Pixar's previous eight features and probably their most original film to date. He said it had the "heart, soul, spirit and romance" of the best silent films. Honeycutt said the film's definitive stroke of brilliance was in using a mix of archive film footage and computer graphics to trigger WALL-E's romantic leanings. He praised Burtt's sound design, saying "If there is such a thing as an aural sleight of hand, this is it."
Roger Ebert writing in the Chicago Sun-Times found WALL-E "an enthralling animated film, a visual wonderment, and a decent science-fiction story". Ebert said the scarcity of dialogue would allow it to "cross language barriers" in a manner appropriate to the global theme, and noted it would appeal to adults and children. He praised the animation, saying the color palette was "bright and cheerful [...] and a little bit realistic", and that Pixar managed to generate a "curious" regard for the WALL-E, comparing his "rusty and hard-working and plucky" design favorably to more obvious attempts at creating "lovable" lead characters. He said WALL-E was concerned with ideas rather than spectacle, saying it would trigger stimulating "little thoughts for the younger viewers." He named it as one of his twenty favorite films of 2008 and argued it was "the best science-fiction movie in years".
The film was interpreted as tackling a topical, ecologically-minded agenda, though McCarthy said it did so with a lightness of touch that granted the viewer the ability to accept or ignore the message. Kyle Smith of the New York Post, wrote that by depicting future humans as "a flabby mass of peabrained idiots who are literally too fat to walk", WALL-E was darker and more cynical than any major Disney feature film he could recall. He compared the humans to the patrons of Disney's Parks and Resorts, adding, "I'm also not sure I've ever seen a major corporation spend so much money to issue an insult to its customers." Maura Judkis of U.S. News & World Report questioned whether this depiction of "frighteningly obese humans" would resonate with children and make them prefer to "play outside rather than in front of the computer, to avoid a similar fate". The interpretation led to criticism of the film by conservative commentators such as Glenn Beck, and contributors to National Review Online including Shannen W. Coffin and Jonah Goldberg (although he admitted it was a "fascinating" and occasionally "brilliant" production).
A few notable critics have argued that the film is vastly overrated, claiming it failed to "live up to such blinding, high-wattage enthusiasm", and that there were "chasms of boredom watching it", in particular "the second and third acts spiraled into the expected". Other labels included "preachy" and "too long". Child reviews sent into CBBC were mixed, some citing boredom and an inadequate storyline. Most critics agree that WALL-E is made more for adults than children.
Patrick J. Ford of The American Conservative said WALL-E's conservative critics missed lessons in the film that he felt appealed to traditional conservatism. He argued that the mass consumerism in the film was not shown to be a product of big business, but of too close a tie between big business and big government: "The government unilaterally provided its citizens with everything they needed, and this lack of variety led to Earth's downfall." Responding to Coffin's claim that the film points out the evils of mankind, Ford argued the only evils depicted were those that resulted from losing touch with our own humanity and that fundamental conservative representations such as the farm, the family unit, and wholesome entertainment were in the end held aloft by the human characters. He concluded, "By steering conservative families away from WALL-E, these commentators are doing their readers a great disservice."
Director Terry Gilliam praised the film as "A stunning bit of work. The scenes on what was left of planet Earth are just so beautiful: one of the great silent movies. And the most stunning artwork! It says more about ecology and society than any live action film – all the people on their loungers floating around, brilliant stuff. Their social comment was so smart and right on the button."