Gamora is the adopted daughter of Thanos, taken from her home planet after Thanos had killed her family. In the film, she is hired by the Collector to secure the Orb, and agrees to aid Ronan the Accuser and her sister Nebula under the pretense of helping Thanos but in truth to prevent the Orb from falling into the wrong hands.
She locates the Orb to be in the possession of Star-Lord, and assaults him on Xandar while he tried to sell the artifact to a merchant. Her attack is hindered, however, as two criminals, Rocket and Groot arrive trying to capture Star-Lord for the high bounty on his head. In the battle, all four are arrested by the Nova Corps and transported to the Kyln prison facility. With her reputation as an assassin and connection to Ronan renown, Gamora becomes a quick target to prisoners and guards alike on the ship, especially by a prisoner named Drax, whose wife and child had been murdered by Ronan. With Gamora being connected to Ronan, Drax attempts to kill her, but Star-Lord arrives on the scene and convinces him to let her live since he can get Ronan through her.
Thankful for Star-Lord's assistance, Gamora explains to him her plan to betray Ronan and gets him, Groot and Rocket to work together to escape the Kyln in exchange for the payment promised to her by the Collector. Initiating the plan, the group creates a prison riot while Rocket rewires the ship's systems and are able to arrive at the docking bay and escape onto Star-Lord's ship, however Drax joins the group due to aiding them during the riot, much to Gamora's chagrin. Once they arrive at Knowhere, the location of the Collector, the group recuperates before delivering the Orb. Star-Lord attempts to woo Gamora, but she rejects his advances, finding Star-Lord to be insensitive towards her. Eventually, they arrive at the Collector's base, where the Collector introduces himself. Examining the Orb, the Collector explains that the Orb in fact holds an Infinity Stone . However, Tivan's assistant, Carina, grabs the Stone to escape from the Collector's torment but its power proves to be too much for her body, and she is destroyed in an explosion of energy, which sends the group flying outside.
Ronan arrives due to Drax contacting him to battle, forcing the others to escape by mining ships and are pursued by Ronan's followers. When they chase them into space, Nebula destroys Gamora's ship, leaving her floating and vulnerable to death. To save her life, Star-Lord ejects himself from his ship and gives her his helmet for her to survive while he summons his former Ravager captain Yondu; Yondu arrives and collects the pair before they succumb to the exposure. Rocket, Drax, and Groot arrive to attack the Ravager ship, but Star-Lord manages to persuade Yondu to help them stop Ronan in exchange for giving him the Infinity Stone to sell. Although the rest of the group is doubtful knowing that fighting against Ronan would cost them their lives, Gamora chooses to fight to prevent many other lives lost by Ronan along with everyone else.
They then set course to Xandar, where Ronan is about to purge the planet. With the aid of Yondu and the Nova Corps, Gamora, Star-Lord, Rocket, Groot and Drax manage to breach Ronan's ship where they are confronted by Nebula. Gamora combats her sister while the others move towards Ronan. Just as Gamora gains the upper hand, Nebula falls with her cybernetic arm clinging on the ship's edge. Gamora tries to lift her up, but Nebula refuses the mercy and cuts her arm off, landing on a ship which she hijacks and escapes. With Nebula defeated, Gamora deactivates the barrier to Ronan's chambers and rejoins the group, but they find themselves completely outmatched by his power until Rocket flies Star-Lord's ship through the ship and collides with Ronan.
The damage causes the ship to crash land on Xandar with the group still in it, but Groot wraps his branches around them to protect the group from impact but sacrificing himself in the process. Ronan emerges from the wreck and dubs the heroes "Guardians of the Galaxy" while stating their efforts to be meaningless and prepares to destroy Xander, but Star-Lord distracts him allowing Drax to destroy Ronan's hammer. Star-Lord grabs the Infinity Stone but its power begins to destroy him until Gamora reaches through the field of energy to Star-Lord and joins hands with him. Drax and Rocket do the same, and they are able to contain its power. With it, Star-Lord uses the Stone to destroy Ronan..
To prevent the Stone from being used to create any more chaos, Quill switches it with a false one to give Yondu while giving the real Stone to the Nova Corps. As a reward for saving the planet, the Nova Corps rebuild Quill's ship and make their team an official protection force, expunging the Guardians' criminal histories as well. Gamora notes to Drax that he had received his revenge against Ronan and his family would be happy, but Drax states that Ronan was only a puppet; Thanos is the one he must hunt down. Taking off in their ship, the Guardians prepare to leave on their next adventure.
Gamora is a leading member of the Guardians of the Galaxy alongside Star-Lord, Drax the Destroyer, Rocket Raccoon and Groot and Nova. The Guardians battle the Chitauri an alien race led by Korvac. When Rocket Raccoon's ship is pulled into the Chitauri ship, Rocket fakes surrender so that they can free the captive Guardians of the Galaxy members. Afterwards, Spider-Man discovers that the Chitauri are planning to destroy the Earth. The Guardians plan to run the Chitauri ship into the sun while fighting the Chitauri forces. When their tactic does not work, the Guardians end up making their way towards the Dark Matter Cannon. While Nova and Spider-Man head to the Dark Matter Cannon, the Guardians fight the Chitauri and Korvac. After Korvac is defeated by Groot, Nova destroys the Dark Matter Cannon and the Chitauri ship is destroyed.
In the episode "The Return of the Guardians of the Galaxy", Gamora was seen recuperating on the Guardians of the Galaxy's spaceship when they land on Earth at the time when Titus leads the Chitauri into targeting Nova's helmet. When she recovers in time to help fight Titus' forces, she voiced her disdain that they had to land on Earth. After Titus was defeated and the remaining Chitauri escape, Nick Fury was displeased that Gamora showed up on Earth again when she said that she wouldn't return. Gamora stated "I lied" and then left with the Guardians of the Galaxy with Titus in their custody.