"Although I've enjoyed writing it every bit as much, my next book will be very different to the Harry Potter series," Rowling said in a statement. "The freedom to explore new territory is a gift that Harry's success has brought me, and with that new territory it seemed a logical progression to have a new publisher. I am delighted to have a second publishing home in Little, Brown, and a publishing team that will be a great partner in this new phase of my writing life."
The Hollywood Reporter said the U.S. publishing company did not divulge the book's title, subject or publication date.
This will mark Rowling's first book since the Potter spinoff "Tales of Beedle the Bard" was released in 2008.
"Harry Potter and the Deathly Hallows," the final installment in the seven-book series about the boy wizard, was published in 2007.
The Potter books were published by Bloomsbury in the United Kingdom and Scholastic in the United States.