Gigatron led the Predacons under direct orders from the Predacon Council. His public mission involved plundering Earth's energy, but his true objective was locating the Autobot battlestation Fortress Maximus. Before reaching Earth, he scorched countless worlds in his quest for supremacy, reducing them to barren husks. Commanding from the Megastar headquarters, he typically dispatched subordinates like Sky-Byte, Slapper, Gas Skunk, and Dark Scream on missions, intervening personally only during critical failures. His initial strategy involved capturing energy expert Dr. Kenneth Onishi and employing a psycho-probe to extract intel on Earth's energy sources and Fortress Maximus's location.

Gigatron transformed into six distinct modes: a robot, a twin-headed dragon, a bat-gargoyle creature, a race car, a spaceship, and a claw. Each mode offered unique combat capabilities, making him unpredictable. During a battle within a subterranean pyramid housing the Orb of Sigma—a key artifact tied to Fortress Maximus—he was crushed beneath the collapsing structure. Energies from the pyramid resurrected him as Devil Gigatron, enhancing his physical form and granting four new transformations: a hydrofoil, a griffin, a pterodactyl, and an elephant. This evolution also bestowed vampiric abilities, enabling him to drain the life energy of others to augment his strength.

As Devil Gigatron, his methods intensified in ruthlessness. He drained the energy of his own Predacon subordinates to fuel his rebirth. Later, he forcibly assimilated Scourge and the Decepticons, transforming them into mindless drones devoid of free will yet bound by absolute loyalty. He unleashed cyber-bats across Earth, forcibly implanting them into all children to brainwash them into servitude. The implantation caused agonizing pain, and removal risked fatal brain damage. He explicitly threatened to kill the children if the Autobots resisted, planning to replicate this strategy planet by planet during his intended universal conquest. In a final bid for sole dominion over Earth, he attempted to collapse the Space Bridge network, aiming to annihilate both the Autobots and his own remaining forces, including loyal Predacons.

His defeat came when Optimus Prime and Ultra Magnus combined into Omega Prime. Using energy gathered from Earth's children through Fortress Maximus, they overpowered Devil Gigatron at the planet's core. He was subsequently imprisoned on Cybertron. In non-English continuities, the character appeared as Gigatron or Devil Gigatron, with subtle variations in his role and fate, though his core arc of seeking Fortress Maximus and undergoing a destructive transformation remained consistent.