And despite lockdown restrictions, schools, nurseries and parents were determined to mark the annual celebration of literacy.
Here’s a selection of photos you shared with us on our Facebook page and via email.
Click through our online gallery to see if you can spot anyone you know.
1. Your World Book Day photos
Emma Cunningham shared this fabulous image of her three-year-old son Jaxson dressed as Hey Duggee.
2. Your World Book Day photos
Leanne Cooper sent us this adorable photo of Leo Johnson, four, dressed as Hulk.
3. Your World Book Day photos
Jessica Scudder shared with us this image of her 'little boy' Charlie, seven, with his copy of One Hundred Steps: The Story of Captain Sir Tom Moore.
4. Your World Book Day photos
"Life’s too boring not to dress up with the kids on World Book Day," says Charlie Brooks, pictured with nine-year-old son Oscar and step-daughter Ruby, who is 10.