"A Berry Royal Christmas" will air on December 16 at 8:30 p.m. on BBC1.
The BBC special, A Berry Royal Christmas, sees the ragged Big British Bake Off presenter (centre), who has written more than 75 cookery books, be a part of the Duke (left) and Duchess of Cambridge on several Royal engagements.
Catherine, Duchess of Cambridge and Mary Berry attend the "Back to Nature" festival at RHS Garden Wisley in September in Woking, England.
This news has added fuel to pregnancy speculations as the Duchess of Cambridge had only missed overseas royal trip during pregnancy or maternity leave in the past.
'My grandmother becoming Queen at a very young age, in the days when it was a man's world, it was very hard for her to make a difference - and she's done it in her own very unique, distinct way.
"In their own unique and distinct way, and you know, my grandmother and my grandfather together are the epitome of public service".
The programme also shows Kate, William and Mary as they join former Bake Off victor Nadiya Hussain to whip up food for an event celebrating emergency services workers, nurses, armed forces personnel and others, that was hosted by the couple at the Rosewood Hotel in London last month. The Duke paid tribute to his parents and grandparents for their charity work: "Growing up both of my parents were hugely charitable".
William also gave a special mention to his late mother Princess Diana for paving the way through her work for the homeless as well as tackling the stigma around aids. My father tell up the Prince's Trust. I obtain that you hear and also you imprint and also you be taught so mighty more by giving a tiny of your time, a tiny of your day, to correct be around'. He's concerned in so many various organisations.
The programme will also see the royal couple take Mary to the charities they support where she will learn more about what they do.