Clooney and his 36-year-old British fiancée Alamuddin were seen arriving in the city via a taxiboat on Friday afternoon. They are expected to be joined by over 100 of their closest friends when they tie the knot this weekend.
Matt Damon and his wife Luciana Barroso were one of the first famous couples seen arriving for the celebrations, which are thought to be taking place at the seven star Aman Resort hotel on the Grand Canal.
American actor Miguel Ferrer was also spotted at Venice airport with his wife Lori Weintraub. Brad Pitt, Angelina Jolie, Cindy Crawford, Lana del Rey and Bono are all expected to attend.
Although the festivities will kick off at the Aman Resort on Saturday, the Telegraph reports the couple will tie the knot officially on Monday with a civil ceremony at Venice's 14th century town hall Ca' Farsetti.
With huge crowds expected to turn out for the occasion, Venice council has announced it will close the walkways nearby for two hours over Monday lunchtime.
With some of the biggest names in Hollywood arriving in the city and crowds of fans eager to catch a glimpse of the newlyweds, the scene in Venice could easily become chaotic - and authorities are enforcing extreme measures especially for the nuptials.
Although the canal can't be closed off, the council are doing everything they can to prevent it from becoming too busy. A spokesperson told the Telegraph that gondolas will not be allowed to linger outside the Aman hotel, and all celebrity guests will be escorted on the canal by police boats.
Sounds like it could be the celebrity wedding of the year. (Sorry Kim and Kanye.)