King-Smith wrote his first book, The Fox Busters, when he was in his 50s. He is best known for penning the 1983 novel The Sheep-Pig, which inspired the 1995 Oscar-winner Babe. His 1990 story The Water Horse was also adapted into a 2007 feature film.
In addition, the prolific author wrote more than 100 other books, which have sold over 15 million copies around the world. Animals and pigs, in particular, were the writer's favorite subject.
Queen Elizabeth II honored King-Smith with an OBE for his work in children's literature last year.
King-Smith is survived by his second wife Zona, three children, 14 grandchildren, four great-grandchildren and one great-great grandchild.