Titles, stories and release dates for the books have not yet been announced. Cameron begins filming the first Avatar sequel next year. The movie is set to be released in December 2016.
Gould is best known for Jumper, about a boy who can teleport through space that was turned into a 2008 film starring Hayden Christensen and Rachel Bilson.
He was a finalist for the Nebula Award and is president of the Science Fiction Writers of America.
"Steven Gould is one of the shining lights in contemporary science fiction," said Cameron. "I've long admired the worlds and characters he's created in his books and stories. We're very fortunate to have Steven bring his formidable talents to the Avatar universe. He is already working closely with me and the screenwriters to flesh out the expanding world of Avatar.