A clutch of photographers were on hand to record the couple's arrival at the Tronchetto terminal, where they were picked up by Clooney's regular water-taxi driver and taken to the luxury Cipriani hotel.
The couple were accompanied by supermodel Cindy Crawford and her husband, among the many celebrities arriving for the festivities.
Among the other arrivals in Venice were actors Matt Damon and Miguel Ferrer.
Clooney, 53, and human rights lawyer Alamuddin, 36, have not publicly divulged details of the celebrations, although Venice city officials have closed the area along the famed Grand Canal on Monday.
As dozens of Hollywood's hottest stars begin descending on Italy for George Clooney's hotly-anticipated wedding to human rights lawyer Amal Alamuddin, the seven-star Aman Canal Grande hotel is pulling out all the stops to ensure everything is picture perfect for tomorrow's wedding reception.
While the couple and Amal's family will be based at the Hotel Cipriani, Venice's only seven-star hotel will host the reception
Tonight, the couple will host friends and family for a lavish dinner at the Cipriani Hotel. Tomorrow morning, guests will indulge in breakfast before making their way, by boat, to the Aman for the ceremony and festivities after,
It won't be an all night affair at the opulent hotel however as they're expected to party into the wee hours of the morning at the Cipriani.
Security has been increased around the area as more than 150 stars, including Bono and Ali Hewson, Cindy Crawford, brad Pitt and Angelina Jolie, are expected to travel to Italy to see Hollywood's most eligible bachelors walk up the aisle.
In spite of the lavish surroundings, this won't be a uptight affair as hotel insiders told the Telegraph that he as a great rapport with bar staff in particular.
“George has a great relationship with all the staff,” a source explained. “He sometimes throws impromptu early morning cocktail parties and the bartenders let him go behind the bar to help out.”
Another source also told Us Magazine the couple are pulling out all the stops to ensure guests have a night to remember.
"Everyone is very excited. It's going to be quite the party," they said. “There is a lot of celebrating planned. They will be serving the tequila at a couple of the parties!”
This will mark his second marriage, after being with actress Talia Balsam from 1989 to 1993. But this time around is said to be different for George, as he has thought about becoming a parent.
"George is saying he's ready to do this - he thought he never wanted children, but meeting Amal has made him realise he is ready for a family," a source told British magazine Closer. "He's so glad that she has come into his life and knows he wants her to be the mother of his kids."
George revealed the reason behind their Italian nuptials simply came back to the star of their love story.
"I met my lovely bride-to-be here in Italy, who I will be marrying in a couple of weeks in Venice, of all places. Amal, I love you to death and I cannot wait to become your husband," he shared at a recent charity event in Italy.
Additional reporting by Press Association