Before his comics career, Kraft worked as a rock and roll journalist. In September 1976, he became editor of FOOM with issue #15, Marvel's self-produced fan magazine, lasting as editor until the magazine's final issue (#22) in 1978.
Known for his offbeat approach, Kraft first made a name for himself as a comic book author with his work on Marvel Comics' The Defenders, particularly the 1977 "Scorpio Saga" story-arc (issues #46, 48–50). In The Defenders, Kraft wrestled with large philosophical issues: the temptations of power, the Cold War and nuclear power, sibling rivalry, and growing old alone. Kraft also merged his interests in music and comics by inserting multiple references to the band Blue Öyster Cult into his Defenders stories specifically the "Xenogenesis: Day of the Demons" storyline, issues #58–60. Kraft combined music and comics in his scripting of the Marvel Super Special #4 featuring The Beatles. Marvel Super Special #7, an adaptation of the film Sgt. Pepper's Lonely Hearts Club Band, by Kraft and artists George Pérez and Jim Mooney were promoted on the "Bullpen Bulletins" page in Marvel Comics cover-dated January 1979. It was never published in the U.S. "because the book was late and the movie proved to be a commercial failure," according to a contemporaneous news account.
Kraft wrote the Man-Wolf feature in Creatures on the Loose and Marvel Premiere and featured the character in The Spectacular Spider-Man Annual #3 (1981). He wrote the entire run, except the first issue, of Savage She-Hulk, which ran from 1980–1982. Kraft worked on such titles as Captain America and scripted the first story drawn by John Byrne for Marvel Comics: "Dark Asylum," published in Giant-Size Dracula #5 (June 1975).
In the early, to mid-1980s Kraft wrote children's storybooks featuring Marvel characters such as Spider-Man, the Hulk, and the Fantastic Four for the Children's Press, Marvel Books, and Simon & Schuster. During this same time, he wrote the interactive gamebooks Ghost Knights of Camelot for Avon, and Robot Race for Scholastic books. In 1983–1984, Kraft wrote World's Finest Comics for DC Comics, including that series' issue #300 (Feb. 1984). After that, Kraft did occasional comics writing but mostly focused his energies on publishing and criticism. In 1995, Kraft worked as a story-editor and scripter for the short-lived animated series G.I. Joe Extreme. Kraft is the co-writer and editor of Yi Soon Shin: Warrior and Defender by Onrie Kompan Productions, LLC.