With Krypton destabilized from mining of the planet's core, Jor-El, chief advisor to Krypton's supreme council, recommends the council give him control of the genetics codex. Before any action can be taken, soldiers led by General Zod, an old friend of Jor-El's, launch an uprising and arrest the councilors. Realising that Krypton is doomed, Jor-El steals the genetic codex sought by Zod and infuses them into the DNA of his infant son, Kal-El – the first naturally born Kryptonian child in centuries. Donning his old armor, Jor-El sacrifices his life to allow his son to escape on a preprogrammed spacecraft. Zod's rebellion is suppressed by the council and are sentenced to the Phantom Zone after being convicted of treason. Krypton explodes soon after.
Following Jor-El's coordinates, the ship crash lands on Earth in Smallville, Kansas. A childless couple, Jonathan and Martha Kent, find Kal-El and raise him as their own, naming him Clark. Clark eventually becomes an isolated young man as a result of developing superhuman powers which he tries to hide from others. He then learns his true origins from Jonathan, who urges him to keep his powers hidden. Several years later, Jonathan dies in a tornado while refusing to let Clark rescue him. Burdened with guilt and looking for a new purpose in his life, Clark leaves to travel the world for an extended period of time under several disguises.
Several months later, Daily Planet reporter Lois Lane receives an assignment to investigate the discovery of a Kryptonian scout ship in the Canadian Arctic. Disguised as a worker, Clark enters the ship and activates its central computer using a key left by Jor-El, which allows him to communicate with an artificial intelligence modeled after his father. The AI explains that Clark was sent to Earth to guide its people, and presents him with a Kryptonian uniform bearing his family's symbol. While following Clark, Lois inadvertently triggers the ship's security system. Clark uses his powers to rescue Lois before wearing the uniform and testing his flying abilities. Unable to convince supervisor Perry White to publish an article on the incident, Lois tracks down Clark and agrees to keep his secret safe.
Escaping the Phantom Zone, Zod and his crew intercept a transmission from the scout vessel and travel to Earth. Deducing that Kal-El is nearby, they broadcast a global address demanding that he surrender or risk war. Clark meets with the United States Air Force and agrees to comply, with Lois joining him as a hostage. Zod reveals that he possesses numerous terraforming devices, the largest called a World Engine, which he salvaged from Kryptonian outposts, which he intends to use to transform Earth into a new Krypton. His science officer, Jax-Ur, extracts Clark's genes to create Kryptonian colonists who will annihilate humanity and build a society based on Zod's ideals of genetic purity.
With help from Jor-El, Clark and Lois flee and warn the U.S. military after an explosive confrontation between Clark and Zod's troops in Smallville, just as Zod orders an invasion. Zod deploys the World Engine from the Kryptonian ship, which touches down in the Indian Ocean and begins firing a beam through the planet towards the ship, severely damaging Metropolis, and initiating the terraforming strategy. Given the codename "Superman" , Clark destroys the terraforming platform while the military launches a suicide attack, sending Zod's troops back to the Phantom Zone. With the ship destroyed and Krypton's only hope of revival gone, Zod vows to destroy the Earth and its inhabitants just to spite Superman. The two Kryptonians engage in a lengthy battle across Metropolis, which concludes when Superman is forced to kill Zod as he attacks a family in a train station.
Superman persuades the government to let him act independently, so long as he does not turn against humanity. To allow access to dangerous situations without attracting attention, Clark takes a job as a freelance reporter for the Daily Planet.
- Channing Tatum as Clark Kent / Superman, A Kryptonian sent by his parents to Earth as an infant to escape the destruction of his homeworld, Krypton, and raised in Smallville, Kansas, under mental guidance of farmers Martha and Jonathan Kent until he is inspired by the holograph message from his late father to become Earth's greatest protector (Superman is depicted as being 33 years old, at least from the moment he is found, in the present timeline of the film).
- Kristen Bell as Lois Lane, A reporter for the Daily Planet newspaper and the love interest of Clark Kent.
- Max Greenfield as General Zod, A Kryptonian general and megalomaniac with the same superpowers as Superman, bent on transforming Earth into a new Krypton under his reign.
- Matt Hill as Jonathan Kent, Clark's adoptive father.
- Tom Kenny as Martha Kent, Clark's adoptive mother.
- Alex Désert as Perry White, Editor-in-chief of the Daily Planet and the boss of Lois Lane.
- Jenny Slate as Faora-UI, General Zod's sub-commander and a commander of the Kryptonian military, who is completely devoted and loyal to Zod.
- Gabriel Iglesias as Colonel Nathan Hardy, A United States Air Force officer, call sign "Guardian", assigned to the United States Northern Command.
- Julie Bowen as Lara Lor-Van, The biological mother of Superman and loyal wife to Jor-El.
- Jerry O'Connell as Jor-El, The biological father of Superman.