Brothers Zach and Gray Mitchell visit Isla Nublar, the site of the original Jurassic Park, where a new theme park named Jurassic World has operated for years. Simon Masrani, the park's owner, has encouraged geneticist Dr. Henry Wu to create a hybrid dinosaur to attract visitors. The two boys meet their aunt, Claire Dearing, the park's operations manager. Claire assigns her assistant Zara to be their guide, but the boys evade her and explore the resort on their own.
Owen Grady, a Navy veteran, has been researching the intelligence of the park's four Velociraptors. InGen Security chief Vic Hoskins believes the raptors should be trained for military use despite objections from Owen and his assistant Barry. Masrani has Owen evaluate the enclosure of the park's new hybrid dinosaur, the Indominus rex, before the attraction opens. Owen warns Claire about the danger of raising Indominus in isolation, pointing out its lack of socialization with other animals. When they discover that the Indominus seems to have escaped, Owen and two others enter the enclosure. Able to camouflage itself and mask its heat signature, the Indominus suddenly appears and devours Owen's companions before escaping into the island's interior. Owen suggests that the Indominus must be killed, but Masrani instead sends a specialized unit equipped with non-lethal weaponry to capture it. After most of the unit is killed, Claire orders the evacuation of the island's northern sector.
While exploring the park in a gyrosphere ride, Zach and Gray enter a restricted area. The Indominus arrives and destroys their sphere, but the boys manage to evade it and find the ruins of the original Jurassic Park visitor center. They repair an old 1992 Jeep Wrangler Sahara and drive back to the park resort. Claire and Owen search for the boys, but encounter the Indominus and barely escape. Masrani and two troopers hunt the Indominus by helicopter, but when the Indominus breaks into the park's aviary to escape the gunfire, it releases a flock of the pterosaurs Pteranodon and Dimorphodon that collide with the helicopter, causing it to crash, killing Masrani and his troops. The pterosaurs then attack the resort itself; in the chaos, Zara is carried off by pterosaurs before falling into the park's lagoon and being devoured by the park's Mosasaurus. Gray and Zach eventually find Owen and Claire at the resort as armed personnel subdue the pterosaurs with tranquilizers.
Assuming command, Hoskins orders that the raptors should be used to track the Indominus; Owen is forced to accept Hoskins's plan and release the raptors. Upon finding the Indominus, the dinosaurs begin communicating with one another. Owen realizes that the Indominus includes raptor DNA, and it becomes the raptor pack's new alpha, taking command away from Owen. The Indominus escapes when the troops shoot at it, and the raptors hunt down and kill most of the team. Hoskins arranges for Dr. Henry Wu to leave the island by helicopter with the dinosaur embryos, in order to protect his research. Owen, Claire and the boys find Hoskins at the lab, with more staff packing up the remaining embryos. Hoskins reveals his plan to create other hybrid dinosaurs like Indominus for use as superweapons, but a raptor breaks in and mauls him to death.
Owen re-establishes his bond with the raptors before the Indominus reappears. The raptors attack the Indominus, but three of the four are killed. Claire lures the park's Tyrannosaurus rex into a battle with the Indominus. The two dinosaurs fight, with the Indominus gaining the upper hand until Blue, the lone surviving raptor, joins the battle. Overwhelmed, the Indominus is backed up to the lagoon, where the Mosasaurus leaps out and drags it underwater. The T. rex retreats, followed by Blue, who turns to acknowledge Owen before leaving. Isla Nublar is once again abandoned, and the survivors are successfully evacuated to the mainland. Zach and Gray are reunited with their parents, while the T. rex roams freely on Isla Nublar.