"My daughter James is losing her mind over it," he revealed of the 4-year-old. "She's never been interested in a movie I've done ever."
Though his youngest daughter isn't too interested in the flick just yet, Reynolds can't wait to see how she responds to it.
"My daughter Inez is 2, and that one is a little strange because she tends to relate more to villains," he said. "We took our kids to The Nutcracker and there's a moment at the beginning where the kid takes the toy and smashes it on the ground and everyone gasps in the audience. My daughter was just like [starts clapping]."
"Even our pediatrician, when she met her, she said, 'Oooh this one... she's shady. Watch out,'" he quipped. "I'm curious how she's gonna react to it. She just loves villains. I'm surprised she's not selling hand-rolled cigarettes at her preschool."
Though Reynolds' kids "can't quite process" his fame yet, he makes sure to "tell them I'm a big deal, but they don't buy it."
"They do know Deadpool," he says of his two daughters. "They sometimes say it and it's sort of embarrassing. I'll be in a grocery store and they'll be like, 'My daddy's Deadpool.' And I'll be like, 'I did not tell her to say that... at all. I mean, she's right, so let's not, you know,' but yeah."
ET's Nischelle Turner recently caught up with Reynolds and he joked that he only took the role after getting James' permission. "She's kinda the arbiter of everything I do, really," Reynolds quipped. "I get permission slips."
As for whether James will be getting the paycheck for encouraging him to take the role, Reynolds admitted, "I think she gets the check for most things."
James' approval for her dad's new role came after she saw a mockup of the film with Reynolds' voice as Pikachu.
"She made us watch it a hundred times in a row. So I was kind of in, even if the script was literally made of old spit, I would have been like, 'Yup, I'm doing it. I'm in,'" he said. "I need more of that validation from my child."
The Proposal star also expressed excitement about seeing the flick in theaters with his wife and children.
"We're gonna go to the theater for sure. Nothing beats the theater experience," Reynolds said. "That's pretty amazing, so to be in a community like that, that's fun."