[1][2] While working as a minister Wyatt began writing in his spare time for Dragon magazine, starting with material for TSR's Masque of the Red Death setting.

"[2] The same year he moved to Wisconsin in hopes of getting a full-time job at TSR, which did not immediately work out, but he kept writing material as a freelance author.

[1] Wizards of the Coast ultimately hired him in January 2000 to work on the D&D game full-time; his first assignment was Monstrous Compendium: Monsters of Faerûn, of which he wrote two-thirds.

Wyatt wrote the text for the series of Art of Magic: The Gathering coffee table books, which reprint illustrations from the cards with details for each plane's lore.

[8] In 2017, Mike Mearls wrote: "It's basically a thing James does for fun, and we don't want to burden it with needing all the work required to make it official".

[16] Wyatt received Origins Awards in 2003 for City of the Spider Queen and in 2005 for the Eberron Campaign Setting, which he co-authored with Bill Slavicsek and Keith Baker.

His other notable works include Oriental Adventures (for which he won an ENnie Award in 2002), Draconomicon, the Draconic Prophecies series, and Magic of Incarnum.