The car was first seen at the Geneva Motor Show in 2005, initially available for the Middle and Far Eastern markets.
The launch of a longer Phantom follows on from the success of the standard length car during the last 12 months. Just under 800 Phantoms were sold in 2005, a 15 year high for the company.
The new Phantom with extended wheelbase offers additional interior space for the rear occupants.
Ian Robertson, chairman and chief executive of Rolls-Royce, said: "The extended wheelbase car came about in response to demand from customers, principally in Japan and the Middle East.
However, it was soon attracting interest from buyers in Europe and the UK. The increased interior space offers even wider scope for individualisation."
The Phantom extended wheelbase is available from UK and continental European Rolls-Royce dealers now and is priced at £254,000.