Wilson is one of 800 authors to sign a petition against age banding
Dame Jacqueline Wilson's new book has been age banded, despite the children's author having joined an online campaign protesting against the practice.
The hardback version of Cookie includes the 9+ age band on its back cover.
Wilson is one of 800 authors to sign the No To Age Banding petition, which is being spearheaded by Philip Pullman.
Cookie tells the tale of a shy girl who is teased at school and terrorised by her father, until she and her mother decide to run away.
In a statement Random House said Wilson had agreed to the banding on the back of the hardback after "close discussion".
"Jacqueline can see the arguments both for and against printed age guidance on books but does retain some reservations about the subject," the statement said.
"She has agreed for age guidance to be put on the cover of Cookie, but Random House will maintain the discussion with her and her agent over the matter and will review the situation on a book by book basis."
Wilson told The Guardian that her future titles would not be age banded, but that as this one had been produced "ages ago" with special "cookie tin" packaging, she had not deemed it worthwhile making a fuss over the inclusion of the 9+ graphic.
"They'd all been done before the controversy started and I felt I couldn't possibly be mean enough to the publisher to say throw away all these jackets," she said.
"I'm not in favour of age banding, but also I can be a reasonable person.
"I particularly felt delighted that Random House had presented the book in such an original way. It would just have been incredibly ungracious to say no thanks."
The decision to introduce age banding to books has caused controversy.
Publishers announced books would carry the guidance rating, indicating which books are suitable for readers aged 5+, 7+, 9+, 11+ and 13+/teen, earlier this year.
Research within the book industry suggested people buying books for children would welcome the guidance.
But many authors and independent booksellers fear the age banding would stigmatise children who are not good readers, and encourage complacency in those reading above their age.
Age banding currently appears on books in the US, with pre-school, 5-7, 8-12 and 13+ categories, but is only implemented by some publishers.