Professional chocolatiers have created an edible replica of St George's Chapel and other sections of the Berkshire landmark - including the front facade and turrets.
The model, which took four days to make and stands two feet six inches tall, has gone on show to visitors at the Cadbury World tourist attraction in Birmingham.
Diane Mitchell, marketing manager at Cadbury World, said: "Our chocolatiers never fail to create something fit for royalty to celebrate a special occasion, but I think the chocolate Windsor Castle may well be their crowning glory.
"The scale of the construction and its minute details make it one of the best yet."
The structure uses the equivalent of 1,111 standard Dairy Milk bars and painstaking features include individually hand-scored bricks, a coat of arms and chocolate flowers.
Diane Mitchell added: "We look forward to sharing the creation up-close with Cadbury World visitors and wish Prince Harry and Meghan a wonderful and very happy life together."
Cadbury marked the birth of Prince Louis by crafting a chocolate rocking horse. It created a chocolate pram for Princess Charlotte and a variety of toys for Prince George's arrival in 2013.
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