In a dystopian future, approximately seven centuries from now, Earth has become a wasteland, overwhelmed by trash and stripped of plant and animal life due to relentless environmental neglect and reckless consumption. The remnants of humanity now inhabit the spaceship Axiom, a vessel that they left Earth on long ago. The Axiom is under the control of a massive corporation named Buy N Large, prominently showcased by its logo on the artificial sun shining in the ship's main concourse. Initially, the plan was for humans to reside in space for just five years while robots known as "WALL-Es," created by Professor Simon, worked to cleanse Earth for future re-colonization. However, after seven hundred years, only one WALL-E, voiced by Ben Burtt, remains.
WALL-E spends his days compacting trash into neat blocks and constructing various structures from the debris. His only companion is a cockroach, and he finds joy in collecting intriguing human artifacts, proudly displaying them in the garage he calls home. Each night, he indulges in watching Hello Dolly on VHS, dreaming of holding a hand while he grapples with his loneliness. One fateful day, he stumbles upon a solitary plant. Unsure of its significance, he knows it requires soil and care, so he gently places it inside an old shoe filled with dirt.
The very next day, a colossal spaceship lands, delivering a new robot named EVE (Extraterrestrial Vegetation Evaluator), voiced by Elissa Knight. WALL-E is instantly taken with her, yearning to hold her hand. However, EVE is quick to demonstrate her firepower, wielding a plasma cannon that can pierce through anything. Initially, she scans the barren Earth in search of vegetation but feels disheartened by the absence of life. Eventually, WALL-E manages to get close to EVE and introduces her to his treasure trove of human artifacts, yet EVE’s reluctance to hold his hand remains. In a moment of revelation, WALL-E showcases the plant he found, triggering EVE's prime directive. She encapsulates the plant within her internal containment unit, alerts the mother ship, and instantly goes into hibernation mode. WALL-E is left in a state of confusion as he strives to keep her safe, shielding her from storms and inviting her to watch the sun set in a serene park.
After several days, the mother ship returns to the Axiom, collecting EVE while WALL-E seizes the opportunity to hitch a ride. As they arrive at the Axiom, EVE remains dormant while WALL-E is examined in the landing bay. Continuing his quest to find EVE, WALL-E encounters humans for the first time, who are shockingly overweight and largely incapable of independent movement, being transported in hover chairs. During an encounter, when WALL-E accidentally topples one of the humans, named John, voiced by John Ratzenberger, he offers his assistance, forging a connection as John introduces himself in return.
After tracking EVE to Captain McCrea’s chambers, voiced by Jeff Garlin, WALL-E finds the Captain just as passive and catered for as the other humans. Enthusiastically curious about Operation Recolonize, McCrea accidentally requires EVE to produce the plant, yet it has mysteriously vanished. Following orders, EVE and WALL-E are sent for repairs, but unbeknownst to them, McCrea grows eager to learn more about Earth. In the repair section, a dramatic misunderstanding leads WALL-E to believe EVE is being harmed. In a heroic bid, he activates her plasma cannon to free her, accidentally releasing other robots in the process. When the Axiom's security robots classify them as renegade robots, tensions rise. EVE, frustrated with the chaos, attempts to send WALL-E back to Earth via an escape pod. However, upon witnessing Gopher place the plant within the pod, WALL-E valiantly endeavors to rescue it but is flung into the void of space. Before the pod explodes, he escapes through an emergency hatch, proudly holding the plant, which leads to an exhilarating moment where EVE joyfully spins in space with him, culminating in an electric kiss.
With stealth, EVE and WALL-E infiltrate McCrea's cabin to deliver the plant. However, Auto, the ship's autopilot voiced by MacInTalk, reveals itself as the culprit behind the plant's earlier disappearance. Autonomy issues prevent it from allowing a return to Earth, convinced the planet is irreversibly uninhabitable. In a pulse-pounding moment, it blasts WALL-E, EVE, and the plant down the garbage chute, confining McCrea within his quarters. In a stroke of wisdom, McCrea uncovers a way to access the ship's communication systems, instructing WALL-E and EVE to reach the central deck, where the plant can activate a machine that will return them to Earth. With the assistance of the robots they previously liberated, WALL-E and EVE confront Auto, who is intent on thwarting their mission. In a twist of fate, McCrea stands on his own for the first time, overriding AUTO's commands just as EVE places the plant into the designated machine, propelling the Axiom back to Earth.
Though WALL-E suffers grave injuries while preventing Auto from collapsing the platform, the ship eventually lands on Earth. EVE rushes him back to his beloved garage, tirelessly working to fix him. WALL-E remains disoriented, failing to recognize her and resolutely going about his garbage compaction. Heartbroken, EVE gently clasps WALL-E’s hand, delivering one last electric kiss, which finally reboots him. Together, they witness Captain McCrea enlightening the other humans on how to care for the newly revived plant and restore life to the planet, indicating that nature’s rejuvenation is already in motion just beyond the city limits, where new plants begin to flourish anew.
