We have been inundated with a wealth of fantastic photos after putting out an appeal for them on Facebook.
This gallery has been updated throughout the day as more and more pictures have been sent over!
MORE: Best World Book Day photos from 2021, World Book Day excitement grips Portsmouth as children become their favourite superheroes
Unfortunately due to the overwhelming amount of photos we were sent and time constraints, we have not been able to feature every single one sent to us today – despite hoping to be able to do so.
But we tried to feature as many as possible - and there are over 50 images in our gallery!
The gallery is at the bottom of this article – and make sure to click through all the pages!
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9. Scarecrow
James Logan, 5, from Portsmouth dressed as The Scarecrow from the Wizard of Oz for World Book Day Photo: Tracie Bucklar
10. Peter Rabbit
Codie-Jax bucklar, 23 months old, from Portsmouth is dressed as Peter Rabbit for World Book Day. Photo: Tracie Bucklar
11. Oompa Loompa
Maisie West age 9 from Fratton dressed as an Oompa Loompa from Charlie and the Chocolate Factory for World Book Day. Photo: Samantha West
12. Where's Wally and Chase
Alfie Couzens, 7, and Finley Couzens, 3, from Gosport dressed as Where's Wally (right) and Chase from Paw Patrol (left) respectively for World Book Day. Photo: Tasha Hutchings