The two horns, believed to have come from Africa and worth an estimated $365,000, were found hidden in the luggage of a passenger who arrived in Ho Chi Minh City on a flight from Doha on Sunday.
The Vietnamese passenger has been taken into police custody for investigation, the report said, without specifying whether the man had been officially arrested.
Illegal hunting of rhinos has risen in recent years to meet surging demand for their horns in parts of Asia, in particular Vietnam where they are highly prized for their supposed medicinal qualities.
Sales of rhino horn are illegal, but a hundred grams costs up to $5,000 on the black market in Vietnam, where people mistakenly believe is can cure anything from cancer to hangovers.
At a major CITES meeting in March, Hanoi was asked to develop a database to track legal rhino horn trophies and to reduce local demand for the substance.