Kitson's first professional work was Spider-Man for Marvel UK. He also drew many stories for 2000 AD, beginning with a Future Shock written by Peter Milligan and others by Grant Morrison, and going on to achieve great acclaim with his detailed work on Judge Anderson (written by Alan Grant).

His first work for DC Comics was a Batgirl special issue followed by other work like a run on The Titans. In 2004, Kitson helped relaunch Legion of Super-Heroes for DC Comics and continued on it for two and a half years ending with issue #31.

Kitson signed an exclusive contract with Marvel Comics in 2007, working on such titles as The Order, Secret Invasion: Fantastic Four, and currently The Amazing Spider-Man.

Comics work (interior pencil art, except where noted) includes:

DC

• Azrael #1-28 (with writer Dennis O'Neil, 1995—97)
• Adventures of Superman #507-519 (1993—95)
• Action Comics #611-614 (1988)
• Batgirl Special (1988)
• Batman: Book of the Dead #1-2 (Elseworlds miniseries) (with writer Doug Moench, 1999)
• Batman/Punisher: Lake of Fire (with writer Dennis O'Neil, 1994)
• Legends of the Dark Knight #146-148 (with Doug Moench, 2001)
• Shadow of the Bat #35-38, 43, 50
• Catwoman The Tin Roof Club (with writer Mindy Newell)
• Empire #0-6 (with Mark Waid, 2003—04)
• Flash and Green Lantern: The Brave and the Bold (one-shot)
• JLA (vol. 3) Year One #1-12 (limited series)
• JSA: All-Stars #3 (8-part limited series)
• JSA Strange Adventures #1-6 (mini-series)
• L.E.G.I.O.N. #1-18 (artist); #25-27, 29-37, 39-43, 46-47 (writer/artist); #48, Annual #3 (writer) (1989—93)
• Legion of Super Heroes (vol. 2) Annual #4 (1988)
• Legion of Super-Heroes (vol. 4) #1-3, 5-7, 10-13, 16-17, 19, 23-28, 30 (with Mark Waid, 2005—07)
• The Titans #37-40, 42-44, 47-50

IPC Magazines

• 2000 AD (Future Shocks): #437, 440, 473, 475, 482, 501 (1985—86); (Judge Anderson): #520-531 (1987); (Judge Dredd): #464-465, 481, 484, 491, 493, 506, 540-541, 557, 562-564, 587, 622, 629-630 (1986—89)
• Judge Dredd Megazine (vol. 2) #18 (1992)

Marvel

• Amazing Spider-Man #558, 574 (2008)
• Avengers/Thunderbolts #1-2 (with Kurt Busiek/Fabian Nicieza, 2004)
• The Order (with Matt Fraction, 2007)
• Iron Man Annual #12
• Secret Invasion: Fantastic Four #1-4 (miniseris) (with Roberto Aguirre-Sacasa, 2008)
• Web of Spider-Man (vol. 2) #2, 4 (2010)
• Wolverine #28-29 (1990)

Marvel UK

• Captain Britain #5, 10 (with Jamie Delano, 1985)
• Spider-Man
• Spacethieves
• Transformers #31-32, 45-46, 48, 50, 59-60, 64 (with Simon Furman, October 1985 - June 1986)

Other publishers

• Batman Annual 1986 (illustrated text story, with writer Grant Morrison) Fish1000.Biz: Lost and Found
• Empire #1-2 (with Mark Waid, Gorilla Comics, May—September 2000)