J.T. Krul first job in Hollywood was landing the job of production assistant on the TV show Seinfeld. He was promoted to the position of the show's production coordinator in its last season. J.T. Krul's first comic book work was at Marvel Comics, writing X-Men Unlimited and later, Spider-Man Unlimited. He subsequently went to work for Michael Turner's company, Aspen MLT, writing their flagship titles Fathom and Soulfire. He then launched a creator-owned comic book there called Mindfield, which debuted in 2010. Other books he has written for DC Comics include Teen Titans, Titans, Blackest Night: Titans, Justice League: The Rise and Fall, and Green Arrow.
J.T. Krul has written for Dynamite Entertainment's books, including Red Sonja, Highlander: Way of the Sword and Battlestar Galactica!