Dr. Jumba Jookiba is arrested and put on trial by the Galactic Federation for illegal genetic experimentation, evidenced by his creation "Experiment 626", a small sentient creature with unparalleled intelligence and strength but also a propensity to cause chaos. Jumba is imprisoned while Experiment 626 is sentenced to exile on a desert asteroid. 626 manages to steal a spaceship and activates the hyperdrive, causing its guidance systems to malfunction and randomly set a course for Earth. 626 crash-lands on Kauaʻi, Hawaii only to be knocked unconscious by passing trucks and taken to an animal shelter. The Grand Councilwoman dispatches Jumba and Agent Pleakley, the Council's expert on Earth, to the planet to have 626 captured discreetly. On Kauaʻi, a young woman named Nani has been struggling with caring for her rambunctious, disobedient, and lonely younger sister, Lilo, following the death of their parents. A social worker named Cobra Bubbles expresses increasing concern that Nani is unable to take adequate care of Lilo. To reduce Lilo's grief of not having any friends, Nani decides to let Lilo adopt a dog. At the shelter, Lilo immediately takes a keen interest in Experiment 626, who is impersonating a dog. In spite of Nani's doubts, Lilo names 626 "Stitch" and shows him around the island. That evening, at the restaurant where Nani works, Jumba and Pleakley try but fail to capture Stitch. The resulting chaos is blamed on Stitch, causing Nani to be fired. The next day, Cobra warns Nani that if she does not find another job, Cobra will have to place Lilo with a foster family. However, Stitch's antics, including evading Jumba and Pleakley, ruin Nani's chances of finding work. Nani's boyfriend, David, invites her, Lilo, and Stitch to take a break and enjoy a day of surfing. While Nani, Lilo and Stitch ride a huge wave, Jumba makes one final effort to capture Stitch from underwater, causing Nani to wipe out, and Stitch unintentionally pulls Lilo down with him. Although everyone survives, Cobra witnesses this event and tells Nani that although she means well, Lilo will have to be taken away. Seeing how much trouble he has caused, Stitch runs off. The next morning, the Councilwoman relieves Jumba and Pleakley of their assignment and gives it to the galaxy's militant captain, Gantu, instead, freeing Jumba to pursue Stitch using less covert methods. Meanwhile, David informs Nani of a job opportunity, which Nani rushes to pursue. Stitch, hiding in the nearby woods, encounters Jumba, who chases him back to Lilo and Nani's house. A fight ensues which destroys the house. Cobra arrives to collect Lilo and take her away. As Nani and Cobra argue, Lilo runs away and encounters Stitch, who reveals his alien identity moments before Captain Gantu captures both of them. Stitch manages to escape before Gantu's ship takes off and is confronted by Nani. Before he can explain, Jumba and Pleakley capture Stitch themselves. Nani demands that they help her rescue Lilo, but Jumba insists they only came for Stitch. When Nani breaks down, Stitch reminds Nani about ʻohana, a term for "family" he learned from Lilo, and convinces Jumba to help rescue Lilo. Jumba, Pleakley, Stitch, and Nani give chase in Jumba's spaceship and rescue Lilo. The Grand Councilwoman appears and prepares to take Stitch into custody and retire Gantu for kidnapping Lilo, but Lilo insists that, as Stitch is her pet under local law, he cannot be taken away. Impressed with Stitch's newfound civility and empathy, the Councilwoman decrees that Stitch will live in exile on Earth and be entrusted into the care of Lilo and Nani, and asks Cobra, who is revealed to be a former CIA agent whom she met in 1973, to watch over them. Together, they rebuild the house, and Jumba and Pleakley become members of Lilo and Stitch's family. The film ends with various footage and pictures of Stitch and his new family's life together.
