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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49. Bo Peep and Jessie
Phoebe, 7, and Felicity, 4, from Waterlooville dressed as Bo Peep and Jessie from Toy Story for World Book Day Photo: Jennifer O'Brien
50. Thing 1 and Thing 2
Mason and Logan Murphy 4 dressed as Thing 1 and Thing 2 from Cat in the Hat for World Book Day. Photo: tina hutchings
52. World Book Day
Teachers dressed up as their favourite characters of their books at Kings Academy Northern Parade, Portsmouth. Picture: Habibur Rahman. Photo: Habibur Rahman