Speaking in an interview with the Sunday People's Take It Easy magazine, Berry described the meeting, which took place at the Buckinghamshire offices of Child Bereavement UK, as a 'surreal' moment.
'Prince William said Kate used my recipes,' the excited cook added. 'They were big fans at a charity auction.'
Asking for advice? Mary Berry meets the Duchess of Cambridge during a charity event in Buckinghamshire
Proud: The Duke and Duchess of Cambridge are fans of Great British Bake Off star Mary Berry
Berry has become a household name since Great British Bake Off first aired in 2010, and has made headlines for her dress sense - and for a number of outspoken attacks.
Last week, she inspired countless column inches when she lambasted Gordon Ramsey for swearing on TV and declared she 'hates Gordon Ramsey's programmes'.
She also criticised other reality TV shows saying: ‘I won’t do Strictly or any of those ghastly reality programmes. I’m A Celebrity would be the end. It makes me shudder.’
Others to feel Berry's ire include feminists, of whom Berry said: ‘Feminism is a dirty word. You’ve got to persuade them [men] gently to do things and, of course, when they come back they say, “Oh, wasn’t that fun?”’
Lucky Prince George! His mother, the Duchess of Cambridge, is said to use Mary Berry's moreish cake recipes
National treasure: Despite her outbursts, 78-year-old Berry holds a special place in the nation's heart
Currently gearing up for the fourth series of Great British Bake Off, which begins on Tuesday on BBC2, 78-year-old Berry also revealed how she stays in TV-ready shape - despite being called on to sample scores of cakes and biscuits for the show.
'I do drink hot water,' she told Take It Easy. 'But I also eat smaller portions. People offer you quiche that is low fat but it tastes disgusting.
'I would rather have the real think or a beautiful cake made with all the right ingredients - chocolate, butter and sugar - but a smaller slice.'