The couple will tie the knot at Westminster Abbey at 11am and this morning William's grandmother Queen Elizabeth conferred the Dukedom on the 28-year-old prince.
William's other titles will include Earl of Strathearn and Baron Carrickfergus.
A statement from Buckingham Palace announced: "The Queen has today been pleased to confer a Dukedom on Prince William of Wales. His titles will be Duke of Cambridge, Earl of Strathearn and Baron Carrickfergus."
Meanwhile, William has chosen to wear the uniform of Colonel of the Irish Guards at his wedding.
The Royal Air Force (RAF) search-and rescue pilot who is commissioned in all three branches of the armed services decided to wear the uniform of his senior honorary appointment in the army.
He will wear a forage cap, gold and crimson sash and gold sword slings but no sword. The uniform was fitted by Kashket and Partners.
William's 26-year-old brother and best man Prince Harry will wear the uniform of a Captain of the Household Cavalry (Blues and Royals).
William spent his last evening as a single man with his father Prince Charles, stepmother Camilla, Duchess of Cornwall, and brother before taking time out to speak with well-wishers who had lined the Mall in preparation for his big day.