Prince William and the Duchess of Cambridge were guests of honour at the summer ball at Houghton Hall, near Fakenham, in aid of East Anglia's Children's Hospices (EACH).
The Duchess is a patron of EACH, which is raising £10m to build a new children's hospice at Framingham Earl, near Norwich.
The final figure from the gala is yet to be announced but officials expect it to top £400k.
Graham Butland, the charity's chief executive, said: 'Everyone at EACH is thrilled with the success of A Taste of Norfolk and the projected figure raised of more than £400k is absolutely magnificent.
'This truly unprecedented event for EACH was only made possible following many months of hard work and dedication from our voluntary committee, led by our patron Emma Deterding and Philippa Pease of Purple Chilli Events.
'This special event enables the nook to be one step closer for so many families, but we still have a long way to go and urge everyone to help in whatever way they can.'
Prince William and the Duchess of Cambridge were guests of honour at the event.
Michelin-starred chefs Galton Blackiston, Sat Bains, Claude Bosi, Tom Kerridge and Mark Edwards composed a special menu, which included scallops, sea bass, venison from the estate, and local strawberries and raspberries in a blueberry and cider coulis.
Meeting the five beforehand, the Duchess said: 'William has to put up with my cooking most of the time.'
The Prince added: 'It's the reason I'm so skinny.'
Around £3m has now been raised towards the new hospice, which will be built on a five-acre wooded site at Framingham Earl, near Norwich. It will offer improved care and support to children with life-limiting illnesses and their families.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here