The British actor, who will play lawyer Arthur Kipps in the upcoming adaption of Susan Hill's scary novel, is asking aspiring writers to upload their short ghost stories to YouTube.com.
The winner will attend the London premiere of The Woman in Black in January (12) and have their entry read aloud by Radcliffe as a special bonus feature on the film's DVD.
Radcliffe says, "All you budding writers out there: Remember it is one per cent inspiration and 99 per cent perspiration. I can't wait to see what spooky stories you guys come up with in the coming months."
The competition opens on Halloween (31Oct11) and ends on 20 December (11).