Quach Lam, 39, was smoking in the toilet on the two-hour flight, Giao Thong newspaper reported on Saturday.
It was spotted by the crew who reported it to authorities upon landing at Noi Bai.
Last month aviation authorities slapped nine-month bans on two men after they refused to pay fines for smoking on domestic flights.
They fined a teenage girl VND2 million ($88) last year for smoking on a flight despite repeated warnings by the crew.
In 2017 flight bans were imposed on 40 people in Vietnam for smoking, fighting or stealing on flights.