Vader captures and tortures Princess Leia, who has hidden the plans inside the droid R2-D2 and sent it to find Vader's former Jedi Master Obi-Wan Kenobi on the planet Tatooine. During Leia's rescue by Obi-Wan's allies Luke Skywalker and Han Solo, Vader strikes down Obi-Wan in a lightsaber duel. Having placed a tracking device aboard their ship, the Millennium Falcon, Vader is able to track down the Rebel base on the planet Yavin 4. During the Rebel attack on the Death Star, Vader boards his TIE fighter and attempts to shoot down Rebel X-wing fighters, but Solo intervenes and sends Vader's ship spiraling off course, allowing Luke to destroy the Death Star.

While conversing with Emperor Palpatine via hologram, Vader convinces him that Luke would be a valuable ally if he could be turned to the dark side. Vader hires a group of bounty hunters to follow Luke's friends, and negotiates with Bespin administrator Lando Calrissian to set a trap for them to bait Luke. After Han, Leia, Chewbacca, and C-3PO arrive, Vader tortures and freezes Han in carbonite and gives him to the bounty hunter Boba Fett. When Luke arrives, Vader overpowers him in a lightsaber duel, severing his hand. Vader tells Luke that he is his father, and tries to persuade him to join the dark side and help him overthrow the Emperor. Horrified, Luke escapes through an air shaft. Vader telepathically tells Luke that it is his destiny to join the dark side.

Thinking that there is still good in his father, Luke surrenders to Vader and tries to convince him to turn from the dark side. Vader takes Luke to the Death Star to meet the Emperor. While there, Palpatine tempts Luke to give in to his anger, which leads to Vader dueling with Luke once again. Realizing that Leia is Luke's twin sister, Vader threatens to turn her to the dark side if Luke will not submit. Furious, Luke overpowers Vader and severs his father's robotic hand. The Emperor entreats Luke to kill Vader and take his place. Luke refuses and the Emperor tortures him with Force lightning. Unwilling to let his son die, Vader throws the Emperor down a reactor chute to his death, but is mortally wounded by his former master's lightning in the process. The redeemed Anakin Skywalker asks Luke to remove his mask, and admits that there was still good in him after all as he dies peacefully in his son's arms. Luke escapes the Death Star with his father's body and cremates it in a pyre on Endor. As the Rebels celebrate the Death Star's destruction and the Empire's defeat, Luke sees the spirits of Anakin, Yoda, and Obi-Wan watching over him.

In addition to being a gifted pilot and mechanic, Anakin has built his own protocol droid, C-3PO. Jedi Master Qui-Gon Jinn (Liam Neeson) meets Anakin after making an emergency landing on Tatooine with Queen of Naboo Padmé Amidala (Natalie Portman). Qui-Gon learns from Shmi that Anakin was conceived without a father and can foresee the future. Qui-Gon senses Anakin's strong connection to the Force and becomes convinced that he is the "Chosen One" of Jedi prophecy who will bring balance to the Force. After winning his freedom in a podrace wager, Anakin leaves with Qui-Gon to be trained as a Jedi on Coruscant, but is forced to leave his mother behind. During the journey, Anakin forms a bond with Padmé. Qui-Gon asks the Jedi Council for permission to train Anakin, but they sense fear in the boy and refuse. Eventually, Anakin helps end the Trade Federation's invasion of Naboo by destroying their control ship. After Qui-Gon is killed in a lightsaber duel with Sith Lord Darth Maul (portrayed by Ray Park, voiced by Peter Serafinowicz), Qui-Gon's apprentice Obi-Wan Kenobi (Ewan McGregor) promises to train Anakin, with the Council's reluctant approval.[86] Palpatine, newly elected as the Galactic Republic's Chancellor, befriends Anakin and tells him that he will watch his career "with great interest".

Sensing that Shmi is in pain, Anakin travels with Padmé to Tatooine to rescue his mother. While there, Anakin learns that Shmi had been freed by and married farmer Cliegg Lars a few years after he left. He then visits Cliegg and learns from him that she was kidnapped by Tusken Raiders. Anakin locates Shmi at a Tusken campsite, where she dies in his arms. Anakin, enraged, massacres the Tusken tribe and returns to the Lars homestead to bury Shmi.[86] Anakin then travels with Padmé to Geonosis to rescue Obi-Wan from Sith Lord Count Dooku. Dooku captures the trio and sentences them to death. However, a battalion of Jedi arrives with an army of clone troopers to halt the executions. Obi-Wan and Anakin confront Dooku, but the Sith Lord beats them both in a lightsaber duel and severs Anakin's arm. After being rescued by Yoda, Anakin is fitted with a robotic arm and marries Padmé in a secret ceremony.

The two Jedi battle Count Dooku, whom Anakin executes at Palpatine's urging. They rescue Palpatine and return to Coruscant. Anakin reunites with Padmé, who tells him that she is pregnant. Although initially excited, Anakin has prophetic visions of Padmé dying in childbirth. Chancellor Palpatine also appoints Anakin to the Jedi Council as his personal representative. Palpatine appoints Anakin to the Jedi Council as his personal representative. Suspicious of Palpatine, the Council allows Anakin as a member, but declines to grant him the rank of Jedi Master and instead instructs him to spy on Palpatine, diminishing Anakin's trust in the Jedi. Later, Palpatine reveals to Anakin that he is the Sith Lord Darth Sidious, and says that only he has the power to save Padmé from dying. Anakin reports Palpatine's treachery to Jedi Master Mace Windu, who confronts and subdues Palpatine. Desperate to save Padmé, Anakin intervenes on Palpatine's behalf and cuts Windu's hand off, allowing Palpatine to kill him. Anakin then pledges himself to the Sith, and Palpatine dubs him Darth Vader.

On Palpatine's orders, Vader leads the 501st Legion to kill everyone in the Jedi Temple, including the children, and then goes to the volcanic planet Mustafar to assassinate the Separatist Council. A distraught Padmé goes to Mustafar and begs Vader to return to the light side. Vader refuses and asks her to help him overthrow Palpatine so they can rule the galaxy together. Seeing Obi-Wan on Padmé's ship, Vader accuses Padmé of betraying him and uses the Force to choke her into unconsciousness. Obi-Wan engages Vader in a lightsaber duel that ends with Obi-Wan severing Vader's limbs and leaving him for dead on the banks of a lava flow, severely burned. Palpatine finds Vader and brings him to Coruscant, where the Sith apprentice's mutilated body is rebuilt with the black armor first depicted in the original trilogy. When Vader asks for Padmé, Palpatine tells Vader that he killed Padmé in his rage, and Vader screams in agony. At the end of the film, Vader supervises the construction of the first Death Star alongside Palpatine and Tarkin.