The two historic dessert portions come in souvenir tins, complete with royal cypher, and each have pre-auction estimates of £400 to £600.
They will go under the hammer at Keys auctioneers in Aylsham in Norfolk, as part of the three-day Fine Sale which begins on November 23.
The King, who was the Prince of Wales at the time, married Camilla Parker-Bowles at Windsor on April 9 2005.
The dedication service took place in St George’s Chapel and the reception was in Windsor Castle’s state apartments.
The wedding cake was made by Mrs Blunden, owner of the ‘Sophisticake’ cake shop in Woodhall Spa, Lincolnshire.
Prince William married Kate Middleton at Westminster Abbey on April 29, 2011, with the reception taking place at Buckingham Palace.
The cake, an eight-tier fruit cake decorated with Lambeth-piped sugar paste flowers, was made by designer Fiona Cairns, based in Fleckney, Leicestershire.
Tim Blyth, director at Keys, said: “With the accession of a new King, and with Prince William subsequently becoming the new Prince of Wales, interest in Royal memorabilia is very high at the moment, and we expect there to be brisk bidding for these two slices of history.”
Other lots on sale at the auction include a Christmas card from Charles and Diana, signed by them both as well as the young Princes William and Harry, which has a pre-auction estimate of £200 to £300.
There is also a photo album with pictures of the late Queen Elizabeth, Duke of Edinburgh and members of the Royal Family, mainly taken on board HM Yacht Britannia during royal visits, with a pre-auction estimate of £300 to £400.
A signed photo of the late Queen and Philip dating from 1980 and a boxed Fortnum and Mason Christmas pudding from 2002, complete with a Christmas card from the late Queen and Duke of Edinburgh, are also up for auction.
The royal lots will go under the hammer during the first day of the three-day sale on Wednesday November 23.