His early work was in comics, as the writer of the James Bond stories Silent Armageddon (1993, drawn by John M. Burns) and Shattered Helix (1994, drawn by David Jackson, with colouring by David Lloyd)) and as a contributor to 2000AD. He left comics largely behind in the mid-1990s, when he moved into script-writing for other media. He has worked on feature-length adaptations of children's fiction and has written scripts for a number of computer games, including the best-selling Fire Warrior and the landmark game/internet serial Halcyon Sun (with Jonathan Clements).

Jowett's broadcast television work includes A.T.O.M. (Jetix/Toon Disney), Chop Socky Chooks (Aardman Animations), Zula Patrol (Zeeter Productions), Pitt & Kantrop (Millimages), The Way Things Work (Millimages) and episodes of Bob the Builder (HIT Entertainment).

He is also the author of two novels and several children's books, including movie tie-ins to Finding Nemo and Wallace and Gromit. He has also contributed short stories and novellas set in the Warhammer 40K game universe to various anthologies published by the Black Library imprint of BL Publishing, a subsidiary of Games Workshop.

• The Enlghtement of Ly-Chee The Wise a 5-page comic strip in The Incredible Hulk Presents #10 (with Andrew Wildman, Marvel UK, 1989)

• James Bond:
• A Silent Armageddon #1-2 (with John Burns, proposed 4-issue mini-series, Dark Horse Comics, 1993)
• Shattered Helix (with David Jackson, 2-issue mini-series, 1994)

• Black Axe (with pencils by Edmund Perryman and inks by Rodney Ramos, 7-issue mini-series, Marvel UK, 1993)
• Wild Things #1-7 (with Duke Mighten, Marvel UK, 1993))
• Dances With Demons (with pencils by Charlie Adlard and inks by Rodney Ramos, 4-issue mini-series, Marvel UK, 1993)
• Marvel Comics Presents #164-167 ("Behold the Man-Thing") (Marvel Comics, 1994)
• Vector 13: "Case One: Extraction Point" (in 2000 AD #988, 1996)