Calero was born January 2, 1972, Miami Beach, Florida. He attended the New World School of the Arts conservatory high school in Miami, Florida, and New York's, Pratt Institute on a partial scholarship.
His work includes Acclaim Comics' licensed-product titles Sliders and The Gathering; Moonstone Books' TV tie-in titles Cisco Kid and The Night Stalker, Platinum Comics' Cowboys & Aliens; IDW Publishing's Masters of Horror: Dreams in the Witch House; and Marvel Comics' X-Factor, during his tenure on which the title was nominated for the Harvey Award for Best New Series (2006). In 2006, IDW announced that Calero will be one of the cover artists on its six-issue The Next Generation TV tie-in miniseries The Space Between, scheduled for 2007.
Calero drew an arc of Legion of Super-Heroes for DC Comics and his new Marvel series, X-Men: Noir, was released by Marvel in December 2008. X-Men Noir: Mark of Cain was released in 2010.
That same year, he drew the Dark Horse Comics relaunch of the former Gold Key and Valiant character, Doctor Solar, Man of the Atom, which was written by Jim Shooter.
Calero has also provided illustrations sporadically for role-playing games, beginning in 1996 for White Wolf. He has done interior artwork for Dungeons & Dragons books for the Forgotten Realms setting, such as Silver Marches, Faiths and Pantheons, and Races of Faerūn.
Calero and illustrator Kristin Sorra co-founded Atomic Paintbrush, one of the first computer-coloring companies working in the comic-book field.