In the Pride Lands of Africa, a lion king rules over the other animals, who celebrate the birth of future king Simba, son of King Mufasa (James Earl Jones) and Queen Sarabi (Madge Sinclair) at Pride Rock. Mufasa's younger brother, Scar (Jeremy Irons), is jealous and resentful of Simba, who replaces Scar as heir to the throne. A few months later, as Simba (Jonathan Taylor Thomas) grows into a curious lion cub, Mufasa gives him a tour of the Pride Lands, teaching him the responsibilities of being a king and the circle of life. Later that day, Scar tricks Simba into exploring an elephant graveyard, forbidden by Mufasa, with his best friend, female lion cub Nala (Niketa Calame), despite the protests of Mufasa's hornbill majordomo Zazu (Rowan Atkinson). At the graveyard, the cubs are attacked by three spotted hyenas, Shenzi, Banzai and Ed (Whoopi Goldberg, Cheech Marin and Jim Cummings) before Mufasa, having been alerted to the scene by Zazu, rescues them and willingly forgives Simba for his actions. Later that night, the hyenas, who are allied with Scar, plot with him to kill Mufasa and Simba, who are both unaware of their intentions.
The next day Scar lures Simba to a gorge and tells him to wait there while he gets Mufasa. On Scar's orders, the hyenas stampede a large herd of wildebeest into the gorge where Simba is. Mufasa rescues Simba, but as Mufasa tries to climb up the gorge's walls, Scar throws him back into the stampede, killing him. After Simba finds Mufasa's body in the gorge, Scar tricks him into thinking that Mufasa's death is his fault and commands him to run away forever. As Simba leaves, Scar orders the hyenas to kill Simba, but the cub escapes. Scar then announces that both Mufasa and Simba were killed in the stampede and steps forward as the new king, allowing a swarm of hyenas to live in the Pride Lands.
Simba, now far from home, collapses in a desert from exhaustion, but is found by Timon and Pumbaa (Nathan Lane and Ernie Sabella), a meerkat and a warthog who nurse him back to health. Timon and Pumbaa then take Simba in to live with them in the jungle, and the lion lives a carefree life under the motto "hakuna matata" ("no worries"). Years later, Simba (Matthew Broderick), now an adult, rescues Timon and Pumbaa from a hungry lioness, who turns out to be Nala (Moira Kelly). The two reconcile and fall in love. Nala tries to get Simba to come back home, telling him the Pride Lands have become a wasteland with not enough food and water. Still feeling guilty over his father's death, Simba refuses and storms off, leaving Nala disappointed and angry.
Wise mandrill Rafiki (Robert Guillaume), a former adviser and friend of Mufasa's, tracks Simba down, telling him that Mufasa is still "alive" and taking him to a pond. There Simba is visited by the ghost of Mufasa in the sky, who tells him that he must take his rightful place as the true king of the Pride Lands. Simba then realizes that he can no longer run from his past and goes back home. Nala, Timon, and Pumbaa join him, and agree to help him fight.
At the Pride Lands, Simba confronts Scar. Scar taunts Simba over his "part" in Mufasa's death, but when Scar pushes Simba to the edge of Pride Rock, he admits that he killed Mufasa. Enraged, Simba jumps back up and forces Scar to reveal the truth to the other lions. Timon, Pumbaa, Rafiki, Zazu, and the lionesses fend off the hyenas while Scar, attempting to escape, is cornered by Simba at the top of Pride Rock. Scar begs Simba for mercy, saying he is family and places the blame on the hyenas. Simba says he does not believe Scar anymore, but spares his life and commands him to forever leave the Pride Lands. Scar meekly walks past him, but then attacks his nephew. After a fierce battle, Simba throws his uncle off Pride Rock. Scar survives the fall, but is attacked and killed by the hyenas, who overheard his attempt to betray them.
With Scar and the hyenas gone, Simba descends from the top of Pride Rock and takes over the kingdom as the rain falls again. Sometime later, Pride Rock is restored to its former glory and Simba looks down happily at his kingdom with Nala, Timon, and Pumbaa by his side; Rafiki presents Simba and Nala's newborn cub to the inhabitants of the Pride Lands and the "circle of life" continues.