The porcelain-skinned Rabbit Hole actress, 43, confessed to a German magazine she had used the face-freezing drug in the past but insisted she had now given it up.
But age-defying Kidman said she stopped getting the injections because it made it difficult to move her features.
"I didn't like how my face looked afterward," she said. "Now I don't use it any more - and I can move my forehead again."
The admission flies in the face of Kidman's previous claims she was "completely natural" and had never used the drug.
Kidman had long been suspected as a devotee of Botox, along with ageless Hollywood stars such as Demi Moore, Jane Fonda, Madonna and Kylie Minogue. But she said she still did all she could to fight the signs of aging.
"I've tried a lot of things [to stop wrinkles], but apart from working out and a good diet most things don't help," she said.