Leeds Libraries invited children to help name the vehicles, which will travel the city on a mission to encourage a love of books and reading from an early age.
Named Sam and Nelly after characters in Nick Sharratt’s popular book, the buses are aimed at children up to five and their parents and carers.
The author and illustrator has even provided colourful artwork for their exteriors and spent two days touring Leeds on the buses as he visited local children's centres and met some of the young readers captivated by his work.
Coun Debra Coupar, Leeds City Council’s executive member for communities, said: “The Story Buses are a fantastic new resource for the city, and will play a key role during the Leeds Year of Reading.
"We want to make sure that every child born in Leeds has access to a wonderful range of resources at Leeds Libraries. Joining the library at an early age provides these life-long benefits.
“Taking our Story Buses into the heart of our communities provides opportunities for families and individuals, young and old, to access facilities that otherwise they may not have been able to.”
The buses will continue travelling around a range of public spots, children’s centres and pop-up locations.
Families will be able to hop on board and meet library staff, who will help them choose books to borrow or take part in fun story related activities.
It is part of a whole programme of activities taking place during Leeds Year of Reading.
Chief librarian Andrea Ellison said: “Leeds Libraries has an amazing under-fives programme and the Story Buses offer an innovative way of engaging children and their families out in their local community.
"We can’t wait to welcome children on to the buses and are especially excited to encourage parents and caregivers who might not have considered going to their local library before to come along.
"Every child and adult in Leeds should feel that the library is for them, and we want to foster this as early in life as possible to ensure that all children have the best start.”
Visit the Leeds Libraries website to find out when a Story Bus will come to your local area or follow @LeedsLibraries on social media for updates.