Plot

In the 29th century, Earth has become a garbage-strewn wasteland due to rampant consumerism and corporate greed. The space around Earth is completely cluttered with several layers of defunct satellites. The cities on Earth are drowning in trash and the pile of trash is higher than several skyscrapers. Seven centuries earlier, the mega-corporation Buy-n-Large (BnL) (who used to own everything from super stores to banks to gas stations) evacuated humanity to space on giant star liners. The plan was to use robots to clean up the garbage while the humans were away from the planet. The initial plan was that humanity could return to the planet in about 5 years.

Of all the trash compacting robots left by BnL to clean up, only one remains operational, Waste Allocation Load-Lifter: Earth-Class (WALL-E) (Ben Burtt). As a compactor robot who has achieved sentience, he is the only one of his kind shown to be still functioning on Earth. He is a small mobile compactor box with all-terrain treads, three-fingered shovel hands, binocular eyes and retractable solar cells for power. WALL·E remains active by salvaging parts from other inactive robots and lives in a large robot carrier truck. WALL-E takes one load of trash at a time, compacts it, and the places it on one of designated piles. Once the pile is high enough, he starts on the next one and so on in a never ending process. The huge machines that were created to deal with the trash problem are now lying in waste themselves.

Although working diligently to fulfill his directive to clean up the garbage, all the while accompanied by his cockroach friend named Hal and music playing from his on-board recorder, he is distracted by his curiosity, collecting trinkets of interest from among the garbage. He stores and displays these "treasures" such as a birdcage full of rubber ducks, a Rubik's Cube, Zippos, disposable cups filled with plastic cutlery and a golden trophy at his home where he examines and categorizes his finds. He ignores items valued by humans, throwing away a diamond ring but keeping the ring box. He neatly organizes his finds at the home he has created, where he watches a video cassette of Hello, Dolly! via an iPod viewed through a large Fresnel lens, mimicking the dance sequences. The planet is beset by huge dust storms that hit the cities occasionally. One day, while on his routine run, WALL-E comes across an abandoned refrigerator and inside it he finds a plant seedling growing out of an old shoe.

One day, WALL-E's routine of compressing trash and collecting interesting objects is broken by the arrival of an unmanned probe carrying an egg-shaped robot named Extraterrestrial Vegetation Evaluator (EVE) (Elissa Knight). EVE is a sleek probe robot whose directive is to verify that planets can have human habitability; she provides plant life as evidence specimens. She has a glossy white egg-shaped body and blue LED eyes. She moves using anti-gravity technology and is equipped with scanners, specimen storage and a "Quasar Ion Cannon" in her arm, which she is quick to use.

EVE has been sent to scan the planet for signs of sustainable life. WALL-E is smitten by the sleek, otherworldly robot and he spends hours watching her doing her job from a distance. On an instance, EVE mistakes the noise made by the cockroach to be a threat and fires her cannon, narrowly missing WALL-E and the cockroach, but terrifying WALL-E. Eventually, EVE discovers WALL-E and the two begin to connect.

During a dust storm Wall-E takes EVE to his unit and shows her all his collectible items. he also shows her how he changes his body parts with spares, when they are damaged. WALL-E shows her his most recent find, a living seedling. EVE goes into standby when she puts the seedling sample into her storage compartment inside her body. WALL-E tries everything to revive her but to no avail. He tries recharging her, electric shocks etc. etc. The probe returns to Earth and then collects EVE and the plant, and, with WALL-E clinging on to the outside of the probe ship, returns to its mothership, the Starliner Axiom.

In the centuries (255,263 days on the ship, 700th anniversary of their 5-year cruise) since the Axiom left Earth, its passengers have degenerated into helpless corpulence due to laziness and micro-gravity, their every whim catered to by robotic machinery. John (John Ratzenberger) and Mary (Kathy Najimy) are 2 such passengers on the Axiom. The humans stay on their hover chairs and have their face covered with a TV screen that keeps them in an artificially induced state of coma.

Even the captain, B. McCrea (Jeff Garlin), is used to sitting back while his robot steering wheel AUTO (MacInTalk) flies the ship. AUTO (pronounced Otto) is the artificial intelligence that is the Axiom's robotic steering wheel and autopilot and handles all true command functions of the ship. AUTO is loyal only to directive A113, to the point of preventing even the captain from deviating from it. McCrea is unprepared to receive the positive probe response but discovers that placing the plant in the ship's Holo-Detector will trigger a hyper-jump back to Earth so humanity can begin recolonization. When McCrea inspects EVE's storage compartment, however, the plant is missing, and EVE blames WALL-E for its disappearance.

EVE is deemed faulty and taken to Diagnostics. Mistaking the process for torture, WALL-E intervenes and releases all the other faulty robots in the process, causing him and EVE to be designated as rogues. Frustrated, EVE tries to send WALL-E home in an escape pod, but they witness AUTO's Gopherbot GO-4 stowing the plant in a pod set to self-destruct.

WALL-E enters the pod in an attempt to retrieve the plant but is then launched into space along with it. EVE then uses an emergency exit to chase after WALL-E, and witnesses the pod explode. WALL-E survives and saves the plant, and he and EVE reconcile, celebrating with a dance in space around the Axiom (when EVE kisses WALL-E for saving the plant).

EVE brings the plant back to McCrea, who watches EVE's recordings of Earth and concludes that they have to go back to save the planet. However, AUTO has been programmed with the secret never-return directive A113 issued after BnL incorrectly concluded in 2110 that the planet could not be saved.

Shelby Forthrigh (Fred Willardt), the CEO of the Buy-n-Large Corporation and President of Earth, is shown only in videos recorded around the time of the Axiom's initial launch in the early 22nd century. Constantly optimistic, Forthright proposed the plan to evacuate Earth's population to space, then clean up the planet so they could return within five years. However, upon discovering that Earth had become too toxic to support life, the BnL corporation soon abandoned the cleanup and recolonization, with Forthright issuing to all Starliner autopilots directive A113 which prevents anyone from returning to Earth, and subsequently dissolved. The message is over 700 years ago, and McCrea believes things would have changed by now.

AUTO also reveals that GO-4 attempted to dispose of the plant on AUTO's instruction. When McCrea countermands the directive, AUTO and GO-4 mutiny, electrocuting WALL-E's circuit board, putting EVE into standby, throwing them both down the garbage chute, and locking McCrea in his quarters. EVE is reactivated by a mouse-like robot. EVE and WALL-E are nearly ejected into space along with the ship's trash, but a Microbe Obliterator (M-O) (a tiny, obsessive cleaning robot with a brush on his arms. He spends his time cleaning up the dirt trail WALL-E leaves behind) has been following WALL-E's dirt trail across the ship, and inadvertently jams the door, prompting the Waste Allocation Load Lifter: Axiom-class (WALL·A) garbage bots to abort the ejection.

The robots help in securing the plant, McCrea and AUTO fight for control, resulting in WALL-E being crushed by the Holo-Detector while trying to keep it open. The struggle attracts the attention of the human passengers, specifically John and Mary, who decide to help EVE and WALL-E to accomplish the mission. The ship tilts dangerously due to the fight for control between McCrea and AUTO and the human passengers are thrown out of their seats. John and Mary save a group of babies that were sliding across the floor. McCrea eventually overpowers and deactivates AUTO, and the plant is inserted into the Holo-Detector, initiating the hyper-jump. Once the ship is back in control, the human passengers stand up on their own 2 feet and come out of the TV induced coma for the first time in centuries.

Arriving back on Earth, EVE repairs WALL-E, but finds that his memory and personality have been erased. Heartbroken, EVE gives WALL-E a goodbye "kiss", which sparks his memory and restores his original personality. WALL-E and EVE reunite as the inhabitants of the Axiom take their first steps on Earth.

During the credits, humans and robots turn the ravaged planet into a paradise, and the plant is shown to have grown into a mighty tree, which EVE and WALL-E rest beneath.