Holly's team and her co-host Phillip Schofield arranged for a huge banner saying "Happy Birthday Holly" to be adorned on the side of a boat.
Looking out from the studio window to see the vessel sounding its horn, Holly exclaimed: "That's amazing, thank you! Well that I was not expecting that, that's for sure. Oh you don't need to make a fuss!"
"I'm planning on eating my way through the day," said Holly Willoughby
"Well what do you get the girl that's got everything?!" said Phillip. "Let's get your name on a boat!"
Holly, who was flooded with birthday messages from This Morning viewers, then shared her plans for the day, which involve a romantic meal with her husband of eight years Dan Baldwin.
The birthday girl was surprised with her name on a boat
"I'm going to lunch with my mum, dad and sister today, and then going out for dinner with Dan," said Holly. "Basically I'm planning on eating my way through the day…"
"Mid-thirties now!" she added. "35… That feels a lot older than 34, you know some birthdays just seem older suddenly?"
Phillip, 53, quipped: "My heart breaks for you!"
Holly was showered with cakes and bubbly at This Morning
The pair then got carried away sampling chocolate truffles that Holly had been given, as well as a multi-layered birthday cake that featured doughnuts and a floating teacup.
The bubbly blonde received dozens of cards, bubbly, gifts and more cupcakes during her presenting duties. Posting a photo from her dressing room, Holly wrote: "Happy birthday to me!!! Thanks for all your lovely messages xxx."
"Love my birthday boat!!!" she captioned another photo.