After several years of working as a cartographer, he began working as a comic artist at Marvel UK, the Britain-based imprint of Marvel Comics. Larroca was working at Marvel UK when he contributed to Dark Angel and Death's Head II. At some point, Larroca began to work on mainstream North American comics, such as DC Comics' Flash. Afterwards, Larroca did a three-year run on Marvel Comics' Ghost Rider, during the mid-1990s. It was not until after his run on Ghost Rider, that Larroca would gain the exposure needed to become known as one of the most prominent comic book artists in The United States.
Following Marvel's experiment with the various "Heroes Reborn" titles, editor Bobbie Chase gave Larroca the task of penciling the return of Captain America, Iron Man, Fantastic Four, the Avengers, and several other superheroes, in the Heroes Return mini-series. After the departure of Alan Davis on Fantastic Four, Larroca was give the reins along with writer Chris Claremont. Larroca and Claremont had a three-year-long run on the title.
Larroca left the title penciling chores in the hands of new writer/penciler, Carlos Pacheco, while Larroca went on to do several issues of Uncanny X-Men, after the departure of Adam Kubert, who left to work on Ultimate X-Men. Larroca then proceeded to rejoin with writer Chris Claremont, on X-Treme X-Men.