In the jungle, Kaa, a Indian python seer, watches as Shere Khan, a Bengal tiger with a crippled leg, breaks jungle law by hunting down a family of humans, with only a child escaping. Bagheera, a panther drawn to the scene, rescues the man-cub, Mowgli, and takes him to a family of Indian wolves being raised by Nisha and Vihaan, only for Tabaqui, Shere Khan's hyena lieutenant, to find the boy before he is chased off. They take the infant Mowgli before the wolf council and Akela, the leader of the pack, to decide his destiny with Bagheera buying his life with a kill and Baloo strong-armed into agreeing. Shere Khan arrives to kill Mowgli, but Akela stops him, saying the boy is now under the protection of the pack and forces Shere Khan to leave. Shere Khan swears he would return.
For many years after, Mowgli lives amongst the wolf pack. One day, Mowgli goes swimming alone and encounters Shere Khan. He manages to escape the tiger but then falls into a pit and is saved by an Indian elephant missing a tusk. Bagheera finds Mowgli and takes him home. Though Bagheera reveals to Mowgli that he is a human and he will be safe if he goes to the Man-Village, Mowgli declares that he wishes to be a wolf. He declares that he will only go if he fails the pack's trial, which would determine if he can become a full member of the pack.
During the trial, Bagheera, acting as a predator to chase the young wolves and test their strength, continually chases Mowgli and causes him to fail when he would have come in first. As Baloo falls out with Bagheera over the issue, Mowgli is kidnapped by the Bandar-log, a gang of Hanuman langurs & macaques, on Tabaqui's orders for Shere Khan. Shere Khan attempts to kill Mowgli while he is unconscious but is stopped by Baloo and Bagheera. During their battle with Shere Khan's monkey minions, they are overwhelmed only for Kaa herself to appear and save Mowgli.
Mowgli learns that Kaa has been watching him the whole time and that she believes that he has the power to change the jungle. She then directs him to face Shere Khan, who is again challenging Akela for Mowgli. Mowgli stops the tiger and Akela's challengers with fire taken from the Man-Village but shames himself in Akela's eyes and is forced to leave for the Man-Village. Mowgli is captured by the villagers, including the British colonial hunter John Lockwood and placed in a cage. Bagheera visits him and sadly tells him to stay, encouraging the boy to gain their trust, as Bagheera once did to escape captivity when he was young. Mowgli slowly comes to enjoy human and village life, being raised by the kindly Messua and learning hunting skills from Lockwood.
However, Mowgli's attitude towards Lockwood changes when he sees that Lockwood hunts for sport and has killed Bhoot, an albino wolf cub friend of Mowgli. He also learns that Shere Khan has driven the wolves loyal to Akela to the edge of the jungle after being informed by Gray Brother. Mowgli meets with Baloo, Bagheera, and the wolf pack, declaring that Shere Khan must die. The animals feel obligated to remain out of the conflict as it would break jungle law to fight Shere Khan. Regardless, Mowgli proceeds with his plan and lures Shere Khan to the edge of the village, where with the help of the bull elephants, he mortally wounds the tiger while Tabaqui flees. However, Lockwood accidentally injures Mowgli with a bullet while trying to kill the tiger and shoots Akela when the wolf saves Mowgli from Shere Khan. Lockwood is stopped and wounded by the broken-tusked elephant before he can do more harm and the other animals rally to Mowgli upon seeing his resolve.
Akela gives Mowgli his blessing to lead the jungle's creatures and the wolf pack before he dies peacefully. Mowgli decides to leave the village behind and returns to the jungle, where he stabs the wounded Shere Khan, finally killing the tiger and ending his reign of terror. Mowgli is re-accepted as a member of the jungle. Kaa goes on to say that with Shere Khan and Lockwood gone, Mowgli gave the jungle a voice. As long as Mowgli lived and watched over it, there was peace in the jungle.
- Rohan Chand as Mowgli, a feral boy who is raised by wolves.
- Matthew Rhys as John Lockwood, a colonial British hunter who hunts animals for trophies and had come to hunt Shere Khan.
- Freida Pinto as Messua, a woman who takes care of Mowgli.
- Andy Serkis as Baloo, a sloth bear and one of Mowgli's teachers.
- Christian Bale as Bagheera, a black panther and one of Mowgli's teachers who was once born in human custody.
- Benedict Cumberbatch as Shere Khan, a vicious Bengal tiger with a crippled front leg and Mowgli's arch-nemesis.
- Cate Blanchett as Kaa, a giant Indian Python, the jungle's seer, one of Mowgli's mentors and the narrator of the film.
- Tom Hollander as Tabaqui, a deranged striped hyena and Shere Khan's companion.
- Peter Mullan as Akela, an Indian wolf and the leader of his pack.
- Naomie Harris as Nisha, an Indian wolf and Mowgli's adopted mother.
- Eddie Marsan as Vihaan, an Indian wolf and Mowgli’s adopted father.
- Jack Reynor as Brother Wolf, an Indian wolf who is the oldest and most loyal of Mowgli's wolf brothers.
- Louis Ashbourne Serkis as Bhoot, an albino Indian wolf cub.