In the 29th century, rampant consumerism and environmental neglect have turned Earth into a garbage-strewn wasteland. Humanity is nowhere to be found, having been evacuated by the megacorporation Buy-N-Large (BnL) on giant starliners seven centuries earlier. Of all the robotic trash compactors left by BnL to clean up, only one remains operational: a Waste Allocation Load-Lifter (Earth Class), or WALL-E. One day, WALL-E’s routine is broken by the arrival of an unmanned probe carrying an Extraterrestrial Vegetation Evaluator or EVE, sent to scan the planet for plant life. WALL-E is smitten by the sleek, otherworldly robot, but she goes into standby when he shows her his most recent find: a living seedling. The probe returns to collect EVE and the plant, and with WALL-E clinging on, returns to its mothership, the starliner Axiom.
In the centuries since the Axiom left Earth, its passengers have degenerated into helpless corpulence due to laziness and microgravity, their every whim catered to by machines. Captain McCrea, used to sitting back while his robotic lieutenant AUTO flies the ship, is taken aback by a positive probe response and learns that placing the plant in the ship’s Holo-Detector will trigger a hyperjump back to Earth so humanity can begin recolonization. The plant proves to be missing from EVE’s storage compartment though, and she blames WALL-E for its disappearance.
With the plant missing, EVE is deemed faulty and taken to Diagnostics. WALL-E proceeds to “free” her along with the other faulty robots, causing them to be designated rogue. Frustrated, EVE tries to send WALL-E home on an escape pod, but they are interrupted when AUTO’s first mate GO-4 arrives and stows the stolen plant in a pod set to self-destruct. WALL-E saves the plant from being lost for good, and he and EVE reconcile, celebrating with a dance in space around the Axiom.
EVE brings the plant back to McCrea, who watches EVE’s recordings of Earth and concludes that they have to go back. However, AUTO refuses, revealing his own secret no-return directive A113, issued after BnL inaccurately concluded centuries ago that the planet could not be saved. When McCrea countermands this directive, AUTO mutinies, electrocuting WALL-E and shutting EVE down, and throwing them both down the garbage chute. McCrea struggles with AUTO while EVE, who has been reactivated by a mouse robot, helps WALL-E bring the plant to the ship’s Holo-Detector. AUTO crushes WALL-E in the Holo-Detector, but McCrea deactivates AUTO, and EVE inserts the plant, initiating a hyperjump.
Arriving back on Earth, EVE replaces WALL-E’s circuit, but finds that his memory has been reset and his personality is gone. Heartbroken, EVE gives WALL-E a farewell kiss, which sparks his memory and restores his original personality. WALL-E and EVE reunite as the humans and robots of the Axiom take their first steps on Earth. During the credits, humans and robots are shown learning to farm, fish, and build, turning the ravaged planet into a paradise, and the plant is shown to have grown into a mighty tree.