The actor revealed that the horror film, which was recently cut by BBFC to make a 12a rating, is "genuinely frightening".
"I would say if you're under 12, you really shouldn't see this film," Radcliffe told E! News.
"I think as a parent, unless you've got an incredibly tough child, I would not go and see this film, because it is genuinely frightening and might buy you a couple of nights of a sleepless child."
Radcliffe went on to say that while taking on such a dark role was a difficult transition, it was an experience helped along by the fact that his godson also took part in the project.
"People have seen me in a schoolboy outfit, so it's a little bit of a leap for them to look at me as something else," he said.
"My godson played as my son in the film. I asked for him to be auditioned. I thought seeing me as a boy and then father would weird people out. I wanted to make sure that the relationship was right and the chemistry was right between me and my son and it is. It really comes across that we know each other."
Radcliffe has previously claimed that audience members were "leaping out of their seats" during initial screenings of The Woman in Black.
Watch a trailer for The Woman in Black below: