The Airbus A380 is understood to have been flying from London to Singapore when a medical episode forced the diversion.
“Our London to Singapore service diverted to Baku in Azerbaijan yesterday due to a medical incident onboard,” a Qantas spokesperson said.
“We apologise to customers for the disruption and are working to get them on their way to Singapore as soon as possible.”
The plane was not forced to make an emergency landing and there was no issue with the aircraft.
However, the diversion saw the crew reach their duty limit for the day, so the flight was not able to continue.
The plane was due for routine maintenance in Singapore, but those checks will now be carried out in Baku, with a specialist A380 engineer being flown in from London.
9News understands Qantas will provide all passengers with overnight accommodation.
The flight to Singapore is expected to resume on Tuesday, September 10, Baku time.