The star has been hosting the show alongside Phillip Schofield since 2009 and there has been speculation about when she might give up her place on the sofa.
Speaking on The Jonathan Ross Show, she said reports about her leaving were "unfair and untrue” and that she loves working with close friend Schofield.
"It hurts sometimes, because it’s so unfair and untrue, so it’s difficult sometimes," she said.
"We’re just incredibly lucky. So no, I’m not retiring.”
Willoughby said she feels "very lucky" to be on the ITV daytime programme.
“The show changes so much, I think that’s the beauty of This Morning," said the mum-of-three.
"Recently it’s had the highest ratings it’s had in 15 years. It’s doing really, really well which is extraordinary for a show that’s been around for as long as it has.
"And I think because it changes and it evolves and it adapts. But I think that show has something to teach us a little bit; as long as we keep evolving and changing and moving on and happy to flow with things.”
Willoughby, 40, said she also feels lucky to share the This Morning sofa with Schofield.
"I can’t imagine a world without him being there," she said. "It just wouldn’t be the same. The magic of that show is us two together when we’re together.
"Fridays are different - Dermot (O'Leary) and Alison (Hammond) have their own unique magic.
"Co-hosts like that don’t come along very often.
"So when they do you have to hold tight.
"I do really love him. I really love him. We’re lucky, we really are."
The Jonathan Ross Show is on Saturday at 10.05pm on ITV and ITV Hub.
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