Kidd is the associate art director at Knopf, an imprint of Random House. He first joined the Knopf design team in 1986, when he was hired as a junior assistant. Turning out jacket designs at an average of 75 a year, Kidd has freelanced for Amazon, Doubleday, Farrar Straus & Giroux, Grove Press, HarperCollins, Penguin/Putnam, Scribner and Columbia University Press in addition to his work for Knopf. Kidd also supervises graphic novels at Pantheon, and in 2003 he collaborated with Art Spiegelman on a biography of cartoonist Jack Cole, Jack Cole and Plastic Man: Forms Stretched to Their Limits. His output includes cover concepts for books by Mark Beyer, Bret Easton Ellis, Haruki Murakami, Dean Koontz, Cormac McCarthy, Frank Miller, Michael Ondaatje, Alex Ross, Charles Schulz, Osamu Tezuka, Gengoroh Tagame, David Sedaris, Donna Tartt, John Updike and others. His design for Michael Crichton's Jurassic Park novel was carried over into marketing for the film adaptation. Oliver Sacks and other authors have contract clauses stating that Kidd design their books.
Kidd worked with writer Lisa Birnbach on True Prep, a follow-up to her 1980 book The Official Preppy Handbook.
Publishers Weekly described his book jackets as "creepy, striking, sly, smart, unpredictable covers that make readers appreciate books as objects of art as well as literature." USA Today also called him "the closest thing to a rock star" in graphic design today, while author James Ellroy has called him “the world's greatest book-jacket designer.”
Kidd has often downplayed the importance of cover designs, stating, "I'm very much against the idea that the cover will sell the book. Marketing departments of publishing houses tend to latch onto this concept and they can't let go. But it's about whether the book itself really connects with the public, and the cover is only a small part of that." He is also known to be humorously self-deprecating about his work with statements such as "I piggy-backed my career on the backs of authors, not the other way around. The latest example of that is The Road, by Cormac McCarthy. I'm lucky to be attached to that. Cormac McCarthy is not lucky to have me doing his cover."
Kidd is as a fan of comic book media, particularly Batman, and has written and designed book covers for several DC Comics publications, including The Complete History of Batman, Superman, and Wonder Woman, The Golden Age of DC Comics: 365 Days, and the aforementioned Jack Cole and Plastic Man. He also designed Mythology: The DC Comics Art of Alex Ross and wrote an exclusive Batman/Superman story illustrated by Ross for the book. Kidd once stated that the first cover he ever noticed was "no doubt for some sort of Batman comic I saw when I was about 3, enough said. Or maybe not enough said: the colors, the forms, the design. Batman himself is such a brilliant design solution." Veronique Vienne, who wrote an eponymous book about Kidd in 2006, described Kidd's Batman fandom as a "childhood obsession and lasting adult passion."
His first novel, The Cheese Monkeys, (Simon and Schuster, 2001) is an academic satire and coming-of-age tale about state college art students who struggle to meet the demands of a sadistic graphic design instructor. The book draws on Kidd's real-life experiences during his art studies at Penn State.
Kidd's second novel, The Learners, finds the protagonist of The Cheese Monkeys drawn into the infamous Milgram experiment, thanks to an incidental newspaper ad assignment. The novel uses the experiment as an extended metaphor for advertising, wherein the "content" is masked and fed – sometimes unwillingly — to its consumers.
It was announced at New York Comic Con 2011 that Kidd would be writing Batman: Death By Design, an original graphic novel.
In 1996, Kidd designed and wrote Batman: Collected. Kidd also worked with fellow Batman collector Saul Ferris on another book of a more particular subject, Bat-Manga!: The Secret History of Batman in Japan, which was released for sale in October 2008.
In early 2008, Kidd started a new wave/alternative rock band, writing and recording music under the name Artbreak. He takes the role of song writing, vocals, and percussion, and while the group began as hobby, Kidd has expressed interest in making a serious project out of it. As of 2008, the group performs across the United States and has a tour schedule on their MySpace. They plan to record their original songs for an album entitled Wonderground.
In 2010, Kidd collaborated with the writing staff of the animated series Batman: The Brave and the Bold on the episode "Bat-Mite Presents: Batman's Strangest Cases!" The episode contained a segment that was heavily inspired by the Batman cartoon from the 1960s.
Kidd lives on Manhattan's Upper East Side. His husband is poet and literary critic J. D. McClatchy.