Studio Warner Bros. announced Thursday that Rowling will write the screenplay for a movie based on "Fantastic Beasts and Where to Find Them," her textbook about the magical universe she created in the Potter stories.
The story will focus on the book's fictitious author, Newt Scamander, and is anticipated to be the first in a series.
Rowling said in a statement the movie "is neither a prequel nor a sequel to the Harry Potter series, but an extension of the wizarding world."
She said the story would begin in New York 70 years before the start of Harry Potter's tale.
Warner Bros. was behind eight Harry Potter movies released between 2001 and 2011.