The Airbus A380 aircraft returned to Singapore's Changi airport "as a result of a cockpit warning relating to a cargo door," the airline said in a statement.
Flight SQ 866 landed safely back at Changi at 2:20 p.m. local time, Singapore Airlines said, adding that passengers would be transferred to a replacement flight to Hong Kong.
The airline did not provide further details about the incident, nor did it immediately say whether the cargo door issue affected cabin pressure, CNN reported.
The replacement aircraft was expected to arrive in Hong Kong at 8:40 p.m., more than three and a half hours after the original scheduled arrival time, according to the Singapore Airlines website.
The double-decker A380 is capable of carrying more passengers than any other commercial aircraft.
Singapore Airlines has 19 A380s, operating on routes from Singapore to destinations like Frankfurt, London and Los Angeles.
On January six, one of the airline's A380 fleet was forced to make an emergency landing in Azerbaijan after suffering a drop in cabin pressure. The plane was flying from London to Singapore and had 467 passengers and 27 crew members on board.