The cakes will be served to patients and staff at the Sibsey Road site and the other hospitals run by the United Lincolnshire Hospitals NHS Trust (ULHT).
Each cake is able to serve 60 portions, adding up to a total of 2,700 servings.
They were made from a recipe which includes 85kg of fruit, 35kg of marzipan, and 30kg of icing sugar.
The cakes have been decorated by individual hospitals.
Pilgrim Hospital catering manager John Spencer said: “Well done to the team at Boston for baking all of the cakes and decorating those for Pilgrim Hospital, and also to the kitchens at Lincoln and Grantham for decorating the ones for their staff and patients.
“It really has been a team effort, and the hard work isn’t over yet.”
On Christmas Day, ULHT plans to serve 1,300 patients plus staff a roast turkey dinner with all of the trimmings.
About 186 turkey crowns have been ordered for the occasion, along with 300kg of sprouts, 310kg of baby carrots, more than 500kg of potatoes, hundreds of pigs in blankets, thousands of stuffing balls, gallons of gravy, hundreds of Christmas puddings and gallons of brandy sauce.
Some of the ingredients will also be used to serve staff and patients wanting a festive roast dinner in the hospitals’ restaurants in the days leading up to Christmas.