Reporters and photographers were not invited to the event near the city of Toulouse, but still got a brief glimpse of the blue-tailed aircraft from outside the fenced-off area, as it rolled out from the paint shop.
The A350-900 model is due for its first take-off this summer, with the first deliveries to airlines scheduled at the end of 2014.
Airbus hopes the 314-seater will compete with Boeing's 787 Dreamliner by being both lighter and more fuel-efficient than previous models.
So far, Airbus - which will also make other models in the A350 series - has received orders for 616 carriers.
In a statement, the company said the Trent XWB engines from Rolls Royce were assembled at the end of March and that "a series of vibration tests" have been carried out.