Trama

A lonely Hawaiian girl befriends a runaway alien, helping to mend her fragmented family.

On the planet Turo, Dr. Jumba Jookiba is convicted by the United Galactic Federation for illegal genetic experimentation after creating Experiment 626, a near-indestructible creature with advanced intelligence and destructive tendencies. Sentenced to exile on a barren asteroid, 626 escapes custody, hijacks a spaceship, and crash-lands on Earth, specifically on the island of Kauai, Hawaii. Disoriented after the crash, 626 is struck by passing trucks and taken to a local animal shelter. Meanwhile, the Federation's Grand Councilwoman offers Jumba early release if he recaptures 626, assigning Earth expert Agent Pleakley to assist him.

On Kauai, teenage Nani Pelekai struggles to care for her younger sister, Lilo, following their parents death in a car accident. The eccentric and lonely Lilo frequently clashes with Nani, whose guardianship is under scrutiny by strict social worker Cobra Bubbles. Facing the threat of Lilo being placed in foster care, Nani tries to create stability for her sister. After overhearing Lilo's wish for a friend, Nani takes her to the animal shelter, where Lilo adopts 626, mistaking him for a dog. She names him "Stitch."

Stitch, desperate to evade capture, causes chaos during his first night with the Pelekais, sabotaging a luau where Nani works. The mayhem results in Nani losing her job, further jeopardizing their family situation. Cobra Bubbles warns Nani to find a new job and instructs Lilo to teach Stitch proper behavior. Despite Lilo's attempts to turn Stitch into a "model citizen," his destructive antics repeatedly undermine Nani's job search.

While surfing with Nani's friend David, Stitch's presence draws the attention of Jumba and Pleakley, whose clumsy attempt to capture him nearly drowns Lilo. David rescues her, but Cobra Bubbles, observing the incident, decides to take Lilo into foster care the next morning. Feeling guilty for the trouble he's caused, Stitch leaves the family. Meanwhile, the Grand Councilwoman replaces Jumba and Pleakley with Captain Gantu to apprehend Stitch. However, Jumba, acting independently, continues his pursuit with less subtle methods.

When Nani leaves Lilo alone to attend a job interview, Jumba and Pleakley track Stitch to the Pelekai house, initiating a battle that results in its destruction. Nani arrives to find her home in ruins, just as Cobra Bubbles arrives to take Lilo. Distressed, Lilo runs into the woods, where she encounters Stitch, who reveals his alien identity. Before Lilo can react, Gantu captures her and Stitch in his spaceship. Stitch escapes but is unable to save Lilo.

Nani pleads with Jumba and Pleakley to help rescue Lilo, but they initially refuse, citing their orders. Stitch, recalling the Hawaiian concept of Shana, which Lilo taught him means "family," convinces them to assist. Together, they use Jumba's spaceship to pursue Gantu and successfully rescue Lilo.

The Grand Councilwoman arrives to apprehend Stitch but is impressed by his reformed behavior. Learning that Lilo legally adopted Stitch as a pet, she allows him to remain on Earth under the protection of the United Galactic Federation. She fires Gantu for his reckless actions. Cobra Bubbles reveals his past as a CIA agent and reassures the Grand Councilwoman of Earth's secrecy, referencing their prior encounter in Roswell, New Mexico.

With Stitch, Jumba, and Pleakley now part of their Shana, the Pelekai family rebuilds their home with help from David and Cobra Bubbles, embarking on a new chapter together.