In 2001, Jason Aaron's eight page Wolverine story won a Marvel Comics talent contest, but it was not until 2006 that he produced The Other Side, a Vietnam War story published by Vertigo and illustrated by Cameron Stewart. The Other Side won the Eisner Award in 2007 for Best Limited Series.
Aaron quickly followed The Other Side with Scalped, an ongoing series also published through Vertigo. The series followed Native American organized crime in the fictional reservation of Prairie Rose. The story was partly inspired by the life of Leonard Peltier, a Native American activist who executed two FBI agents during a shootout on a reservation. Elements of this real-life incident were incorporated into one of the series' main characters, Chief Lincoln Red Crow.
Quickly, Aaron was picked up by Marvel Comics and signed to an exclusive contract that did not affect his continued work on Scalped. He wrote the Get Mystique! story arc for Wolverine and was then assigned as the new regular writer of the Ghost Rider ongoing series. He continued to write Ghost Rider until the series ended and wrapped up his run in the Ghost Riders: Heaven's on Fire limited series. Despite the cancellation due to low sales, his Ghost Rider run was well received by fans.
While writing Ghost Rider, Aaron also launched Wolverine: Weapon X as an ongoing series and secondary Wolverine title. This series ended after sixteen issues but only so Aaron could immediately launch the new Wolverine ongoing series, essentially continuing his work on the character. He also wrote PunisherMAX, creating versions of Kingpin and Bullseye unique to Punisher's MAX continuity, and Ultimate Captain America, debuting the Ultimate Universe version of Nuke.
Coming out of his success with Wolverine, Aaron became the writer of Schism, a major X-Men event revolving around in internal civil war among mutantkind between Cyclops and Wolverine.