Clooney, 53, revealed the news that the couple will tie the knot in Venice, where he first met Alamuddin, 36, at a charity gala in Florence, reported Us magazine.
Clooney's and Alamuddin's parents will be present for the formal ceremony on Friday, while friends and other family members will gather in Venice on the weekend of 27 September (14) for a more celebratory affair, a source said.