When Ayesha had sent her fleet of drones on the Guardians of the Galaxy team following the reason Rocket Raccoon had stolen their batteries after defeating the Abilisk, Ego appeared and destroyed the fleet while the Guardians crashed on a nearby planet. On the planet, Ego met with the Guardians and revealed himself as Quill's father. During the meeting, Ego attempted to make Quill return to his home accompanied by Gamora and Drax while Rocket and Groot guarded on Nebula.
When Yondu Udonta and the Ravagers arrived to capture Quill and to hand him over the Sovereign after being hired by Ayesha, Nebula tricked Groot to free her, while Taserface carries out the mutiny against Yondu and executes his loyalists with the help of Nebula, who leaves to kill her sister as revenge for being installed with cybernetic and robotic body parts by their father Thanos.
Yondu, Rocket, and Groot are taken as hostages by Taserface and his men, while Drax, Quill, and Gamora meet with Mantis, Ego's assistant which he raised. Nebula arrives on Ego's planet and attempts to kill Gamora, who survives and defeats her sister via a blaster gun, however, she is reaching to an uneasy alliance point, and the two are exploring the planet. Gamora and Nebula are discovering thousands of skeleton remains hidden inside the caves of Ego's planet, and feeling that Ego is hiding a secret from them.
While still meeting with Quill and Drax, Ego explains that he is one of the god-like Celestials, and exists in the form of the planet on which they are standing. He assumed a human guise to travel the universe and interact with other species, eventually meeting and falling in love with Quill's mother Meredith. After Meredith's death, Ego paid Yondu to collect the young Quill, but Yondu never delivered the boy, and Ego had been searching for his son ever since.
He teaches Quill to manipulate the Celestial power within the planet. Ego reveals to Quill that in his travels to thousands of worlds, he planted seedlings upon thousands capable of terraforming them into new extensions of himself, but they could only be activated by the power of a second Celestial. To that end, he impregnated hundreds of women and hired Yondu to collect the children; they all failed to access the Celestial power, so Ego killed them until he found Quill.
Ego uses Quill to activate the seedlings, which begin to consume every world. Quill is hypnotized into helping Ego but fights back after Ego reveals that he deliberately caused Meredith's death.
Mantis then grows close to Drax and warns him, Gamora, and Nebula of Ego's plan just as Rocket, Yondu, Groot, and Kraglin arrive. The reunited Guardians reach the core of the planet, where Ego's brain is housed. When Ego prepared to fight them, Mantis, with encouragement from the Guardians, was able to put Ego into a sleeping state, giving them time to prepare to destroy him. However, Sovereign's drones arrived to destroy them. While the other Guardians fight the drones, Rocket makes a bomb out of the stolen Anulax batteries, and tries to instruct Groot on properly and safely activating the bomb. With Nebula using herself as a power source for their ship, it was able to destroy all the drones, but one dead drone struck Mantis, knocking her out causing Ego to awaken. Groot plants on Ego's brain, while Quill battles Ego with his newfound Celestial powers to allow the other Guardians to escape.
The bomb explodes, killing Ego and causing the planet to disintegrate. Yondu sacrifices himself to save Quill, who comes to realize that Yondu did not deliver him to Ego in order to spare him from the fate of Ego's other progeny and that Yondu was Quill's true "daddy".
- "I told Gamora how when I was a kid, I used to pretend David Hasselhoff was my dad. He's a singer and actor from Earth, really famous guy. Really never struck me, Yondu didn't have a talking car but he did have a flying arrow. He didn't have the beautiful voice of an angel but he did have the whistle of one. Both Yondu and David Hasselhoff went on kick-ass adventures and hooked up with hot women and fought robots. I guess David Hasselhoff did kind of end up being my dad after all, and it was you, Yondu. I had a pretty cool dad."
- ―Star-Lord about Yondu
Once again accepted as heroes, the Guardians organized a funeral for Yondu, which was attended by several other Ravager factions. During the funeral, Nebula bid Gamora farewell and set out to kill Thanos despite her adopted sister's plea to join the Guardians. Kraglin Obfonteri later presented Quill with a Zune to replace his destroyed Walkman.