Zuo Lei took money from the bag of a Vietnamese passenger sitting in front of him on the flight from Da Nang to Hanoi, police said Wednesday.
About 20 minutes after takeoff Thursday last week, some passengers spotted the Chinese man acting suspiciously. He changed seats and opened a bag from the overhead compartment before rummaging through it.
They immediately alerted the flight attendants who asked passengers sitting close to the man to check their luggage. One of them, whose identity has not been revealed, claimed that he had lost VND10 million ($431) from his bag.
The flight crew checked Lei after he returned from the toilet and found the money on him.
The crew handed the alleged thief over to security authorities at Noi Bai Airport. He is in custody of Hanoi police for investigation.
Many Chinese have been caught for theft aboard flights in Vietnam in recent years. Vietnamese authorities have yet to take effective measures against such theft.
Vietnam Airlines has responded by training staff to be more alert, a representative said.
The national airline has also warned its passengers not to keep money and other valuable assets in their cabin luggage.
Vietnamese laws treat theft as a criminal offense if the stolen property's value exceeds VND2 million ($87).