The couple - who revealed their engagement to the world last week - will tie the knot at Westminster Abbey in London and the date will be a public holiday in the UK.
The venue has extra significance for William as it was the venue for his mother Princess Diana's funeral in September 1997.
At a briefing at St James's Palace, the prince's private secretary Jamie Lowther-Pinkerton said: "The couple have chosen to be married at Westminster Abbey on the Feast of St. Catherine on Friday 29th April.
"The couple were moved to choose the venue because of its staggering beauty, its 1,000 years of royal history and its relative intimacy, despite its size.
"The venue has long associations with the Royal Family - it is in many ways the Royal Family's church - and of course with Prince William personally.
"They're on cloud nine like any other newly engaged couple and they're now getting stuck into organising their wedding. I've never seen two happier people which is fabulous."
British Prime Minister David Cameron has confirmed the day will be a national holiday, saying: "The wedding of Kate and William will be a happy and momentous occasion. We want to mark the day as one of national Celebration - a public holiday will ensure the most people possible will have a chance to celebrate on the day."
It has been revealed the cost of the wedding and honeymoon is going to be shared by the Royal Family and the Middletons, but the costs incurred for things such as security and policing will be will be picked up by taxpayers.
Mr. Lowther-Pinkerton added: "The details of who pays for what haven't been worked through yet but the Middleton family are very, very keen to contribute.
William - who is second in line to the British throne - and Kate want the nuptials to be "a classic British occasion" and "a classic Example of what Britain does best".