NatWest said consumers should be aware that some products appearing to be advertised by a celebrity might be "too good to be true".
Ms Willoughby and her This Morning co-presenter Philip Schofield jointly topped NatWest's league table of famous people exploited in scams.
One customer of the bank transferred over £370,000 to a fraudster as part of a cryptocurrency investment scam which purported to be the pair - but they actually had no involvement whatsoever.
On social media, the customer saw a cryptocurrency scam purporting to feature the ITV presenters, believing they would be able to make sizeable gains from an investment in crypto, which actually resulted in a loss.
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