Willoughby, who is best known for her presenting work across ITV, will lend her voice to a programme for the soft drink.
Speaking on the partnership, she said: “I’ve always been a big Diet Coke fan, right from the original ‘Break’ ads we all remember with great fondness. The brand is well known for celebrating friendship, fashion and fun, which are all very important to me. I’m excited to be involved.”
Simon Harrison, operational marketing director for Coca-Cola European Partners GB, added: “We’re proud to be working with Holly to bring some extra sparkle to Diet Coke activity this year. She’s the perfect partner for us. We’re looking forward to sharing what we have planned with Holly – watch this space.”