Kate Moss to star in new TV series
Kate will make her cameo in the new TV series this Christmas and she will be joined by Jennnifer Saunders and Meera Syal along with 12-year-old newcomer Billy Kennedy.
Walliams said: "We have put together a dream cast for this, the first of my children's books and for many, still my best. It is a funny and poignant story about what it is to be different. I hope it will make everyone who sees it, young and old, stop and think."
It is thought that Kate will play herself in a dream scene.
The Boy in the Dress will be released by the BBC this winter.