The 984ft vessel left the dry dock at the Blohm & Voss shipyard in the early hours and set sail for Southampton, where she was to undergo sea tests.
All five restaurants and 900 cabins on the 13-storey ship have been revamped. Bathrooms were redecorated and some inlaid with marble.
The final touches, such as laying carpets, were being taken care of en route to Britain by 50 craftsmen who have sailed with her.
Cunard launched the refit in New York on 14 November by donating 1,500 pieces of used furniture to a US charity.
The QE2's new trappings include 2,252 new light fixtures, 12 pieces of commissioned artwork and 10,000 pints of lager stocked in a new English pub, the Golden Lion.