Birtwhistle won GBBO in 2014, and will be joining part of The Great British Cruise, an 11-night voyage on board Braemar, which departs from Southampton on 8 August.
She will be on board between Cardiff and Rosyth and will take part in a question-and-answer session, where the cruise director and audience will be able to ask her questions about her time on GBBO and glean baking tips.
Hull-based Birtwhistle will also be hosting a live baking demonstration on board, and will be spending time meeting Fred Olsen’s guests around the ship during her stay.
A self-taught baker, who only decided to pursue her passion seven years ago, when she retired as a GP’s practice manager, Birtwhistle said some of her first memories of baking were Christmases with her grandmother.
Birtwhistle said: “I am absolutely thrilled to be joining The Great British Cruise this year. We will enjoy the best that the British Isles has to offer and I look forward to sharing some of my Bake Off stories, along with some very special cooking and baking secrets.”