It's the year 2775 and Earth has been abandoned for centuries by humans whose trash eventually overwhelmed the planet. The one entity still at work, however, is a little trash collector robot known as WALL·E (voice of BEN BURTT), short for Waste Allocation Load Lifter Earth-Class. He spends his days scooping up and compacting garbage, but has developed an interesting glitch in the form of curiosity, a friendship with a little cockroach, and the desire to collect various discarded items that he keeps as trinkets.
Among them is a tape of the Hollywood musical "Hello, Dolly!" that has given him a glimpse of what part of human life was like long ago, as well as a desire for love. He thinks he may have found it when a spaceship unexpectedly lands on Earth and deposits an Extra-terrestrial Vegetation Evaluator known as EVE (voice of ELISSA KNIGHT).
She's a sleek and futuristic probe sent by those onboard the Axiom, a state of the art mother ship created long ago by Buy n Large CEO Shelby Forthright (FRED WILLARD). Now run by the Captain (voice of JEFF GARLIN) with the aid of a lieutenant robot, Auto (voice of MACINTALK), the ship is filled with thousands of sedentary humans, such as John (voice of JOHN RATZENBERGER) and Mary (voice of KATHY NAJIMY), whose every needs, including that of moving about, are fulfilled by robots.
While there's little hope that EVE will actually complete her prime directive -- finding evidence that Earth has once again become inhabitable -- she's shocked to discover that WALL·E has found a lone plant. She immediately places it into her small cargo hold and then goes inactive, awaiting a return to the Axiom. But this doesn't sit well with WALL·E who longs for the simple romantic gesture of holding hands.
Thus, when her transport ship returns, WALL·E hitches a ride back to the Axiom where his arrival, Earth dirt and all, doesn't sit well with cleaner robot M-O (voice of BEN BURTT). From that point on, and as the Captain and Auto have different reactions to the presence of the plant, WALL·E does what he can to try to rescue his new friend.