Prince William will marry Kate Middleton wearing the famous red tunic of the Irish Guards.
In place of the bearskin, which is worn on ceremonial occasions, he will instead wear a simple cap.
The groom became honorary colonel of the regiment in February.
And St James's Palace has said that he chose the uniform in honour of what is his highest rank.
"If he had not gone for that he would have had to choose between his RAF and Household Cavalry uniforms, and because he is a similar rank in both of those, it would have been quite a difficult decision."
Many had anticipated that William would wear the light blue dress of the RAF, with whom he is currently serving as a flight lieutenant.
William's best man Prince Harry will take his brother's side smartly dressed in the officer's uniform of the Blues and Royals.
The boys' father Prince Charles, meanwhile, will wear the full Royal Navy Number One ceremonial uniform, reflecting his honorary rank as an Admiral.
Photo: © PA