The former Beatle has signed on to publish "High in the Clouds: An Urban Furry Tail" for the Penguin Young Readers Group, the publisher announced Wednesday.
McCartney will team up with veteran children's book author Philip Ardagh and animator Geoff Dunbar. The picture book is to be released this October with a first print of 500,000 copies.
"Having worked on this story and the characters for many years, it's very exciting for me to see things come to fruition in what I think will be a remarkable book," McCartney said in a statement.
The book's story was inspired by an animated film called "Tropic Island Hum," on which Dunbar and McCartney collaborated. It will follow the story of two friends, a squirrel and a frog, who save a number of animals.
The 62-year-old McCartney was announced Tuesday as part of the slate for the new Live Aid concerts. He has five children of his own: four from his first wife, Linda McCartney, who died of cancer in 1998, and a 1-year-old daughter with his wife, Heather Mills McCartney.