The couple left Anglesey on Monday, jetting off on a private jet to a tropical destination.
The exact location of their break is being kept a closely guarded secret, as is the length of time they'll stay there.
A Clarence House spokesperson said: "We are not confirming, and we are not commenting, on speculation on where they may be going on their private honeymoon.
"We are just confirming they have gone."
Prince William has taken two weeks leave from his post as an RAF search and rescue pilot.
He spent one week back at work following the wedding, but not before the couple had enjoyed a weekend break at a secret UK destination.
There has been much speculation as to where William and his new wife are going this week. It's been said that not even Kate knew until the last moment.
Africa, Jordan, the Caribbean and Australia have all been mentioned as possible locations.
Latest reports have pointed to the Seychelles, where the newlyweds will apparently relax in an exclusive villa which normally costs thousands of pounds a night to rent.
The Indian Ocean paradise – which consists of 115 islands featuring miles of white sandy beaches – is one they're familiar with.
In 2007 the couple enjoyed a holiday in Desroches, which lies about 150 miles south west of the Seychelles' main island, Mahe.
It was there the sweethearts rebuilt their romance after reconcilling following their brief split.
The lovebirds – who cheekily checked in under the names Martin and Rosemary Middleton - stayed in a luxurious £500-a-night suite containing a romantic four-poster bed and overlooking a stunning lagoon.
It's been reported the Prince told locals the holiday was the best break he's ever had.
Watch: Prince William takes George to meet his sister
It's a little princess!