In an animated sequence, a plane flying through the Bukuvu region in the heart of Central Africa crashes. A child on board the plane, George, disappears into the jungle and is raised by a sapient, talking gorilla named Ape. Twenty-five years later, George, who enjoys swinging on vines to move about but has a habit of crashing into trees, has grown to be King of the Jungle.
Ursula Stanhope, a San Francisco heiress, tours Burundi with local guide Kwame and a trio of porters. Ursula is tracked down and joined by her fiancé, Lyle Van De Groot, with two poachers named Max and Thor. Kwame tells the group of the “White Ape”, a local legend of a superhuman primate that rules the jungle. The next day, Lyle, insistent on taking Ursula home as soon as possible, goes into the jungle with her to find the White Ape and they are attacked by a lion. Lyle knocks himself out trying to flee while Ursula is saved by George. George takes Ursula to his treehouse home and cares for her, introducing her to Shep, an African bush elephant that acts like George’s dog, and Tookie, a toco toucan. George is smitten with Ursula and attempts to woo her; Ursula reciprocates his attraction, and her time spent with George makes her no longer wish to return home.
Lyle, Max and Thor find the treehouse and Lyle confronts Ursula and George. Max and Thor make to shoot Shep for his ivory, and Ape shouts at Shep to run. Everyone is stunned by the sight of a talking ape and Max and Thor decide to tranquilize and capture him. George runs to stop them and is accidentally shot by Lyle, who thought his gun was a novelty lighter. Lyle and the poachers are imprisoned and Lyle is identified as the shooter by the porters; Max and Thor are released and resolve to capture Ape to make a fortune in Las Vegas. Meanwhile, Ursula takes George home to get medical help for his wound and to see the human world he belongs in.
While Ursula is at work, George explores San Francisco and uses his vine-swinging to rescue a paraglider that got tangled in the Bay Bridge. Ursula, uninterested in marrying Lyle, admits the truth to her parents, but her overbearing mother Beatrice objects. At a party intended to celebrate Ursula’s engagement, Beatrice takes George aside and coldly tells him she will not let Ursula’s engagement fall apart, and refuses to let George be with her. In Africa, Max and Thor capture Ape, who manages to order Tookie to find George before he falls unconscious. Tookie flies to San Francisco and George returns to the jungle, leaving Ursula in the night. While Ursula’s parents comfort her, she realizes she loves George and goes to find him, much to Beatrice’s dismay but to her father’s approval.
Ape tricks the poachers into circling the jungle and returning to the treehouse where George confronts and fights them, eventually incapacitating them with a little help from Ursula and his animal friends. However, Lyle arrives: the narrator explains that Lyle escaped prison, joined a cult, and is now an ordained minister. Lyle has the mercenaries he brought with him subdue George and takes Ursula to the nearby Ape River, where he has a boat waiting to escape while he performs a marriage ceremony. However, the river is a harsh series of rapids that hurtle the two into danger. George escapes the mercenaries and performs a big swing to reach Ursula and Lyle, only to crash into a massive tree. However, the tree falls over the river and he pulls Ursula to safety. Lyle ends up in a cave and, believing he is still sharing the boat with Ursula, proclaims them wedded; he lights his lighter and beholds that he just married himself to a gorilla.
George and Ursula fall in love with each other and marry, Ursula moving into George’s treehouse. Some years later, the two are raising a son, George Jr., who they present to the animals from atop Pride Rock.
In a mid-credits scene, Ape reveals he has become a famous entertainer in Las Vegas, using Max and Thor as stuntmen.