Airbus said the individual, “not from Europe or the US”, would use the plane for “personal use for him and his entourage”, AFP news agency reported.
The double-decker, which is thought to have cost $300m (Â£150m), has 900 sq m (10,000 sq ft) in cabin space and has room for up to 840 passengers.
It is expected to take more than a year to convert the jet for private use.
Aage Duenhaupt, a spokesperson for Lufthansa Technik, which turns large commercial planes into private jets, said the majority of clients were originally Middle Eastern.
But using the model as a private jet could be problematic, because its weight and size mean it can only be landed at a limited number of airports, by certain pilots.