Child will be published on 31 July.
The book is a based on the two-part stage collaboration of J.K. Rowling, Jack Thorne and John Tiffany and arrives just after the play premieres in London on 30 July.
Rowling's Potter web site www.pottermore.com will release an edition.
The first seven Potter books have sold more than 400 million copies worldwide, according to Scholastic, the series' U.S. publisher.
Rowling also shared the news on her Twitter account revealing the possible cover of the new book: