Hosting was transferred to EduServ, a small, not-for-profit organisation that already works with a number of public sector Web sites.
Whitehall sources have confirmed that the migration from its previous undisclosed location took place late last week.
Officials have refused to confirm the exact location of the new site, although there has been speculation that it is in the West Country.
The move follows the termination of negotiations with previous supplier BT earlier this year.
Government officials have described the move as an interim solution while the new version of UK Online is being developed.
The second version of the site will be launched early next year.
A Cabinet Office spokeswoman said, "The long-term hosting partner for UK Online will be decided by a tendering process next year."
In July the Government launched the ninth "life episode" for UK Online, which deals with pensions and retirement.
Existing life episodes on the site cover events such as learning to drive, moving home, having a baby and dealing with bereavement.
Launched by Tony Blair in September 2000, UK Online links more than 1,000 government Web sites. It is part of Blair's plan to make all government services available electronically by 2005.