Currently there are no direct flights Sofia to Hong Kong.

Flights Sofia to Hong Kong with 1 stopover:

Flights via London Heathrow (LHR), London, United Kingdom
From Sofia (SOF), Bulgaria with British Airways Transfer at London Heathrow (LHR) Then on to Hong Kong (HKG), China with Virgin Atlantic Airlines
Flights via Moscow Sheremetievo (SVO), Moscow, Russia
From Sofia (SOF), Bulgaria with Aeroflot
OR
From Sofia (SOF), Bulgaria with Aerosvit
Transfer at Moscow Sheremetievo (SVO), Moscow, Russia Then on to Hong Kong (HKG), China with Aeroflot