Koong Menh was arrested near the border in Huong Son District by the police forces of Ha Tinh and Laos’s Bolikhamsai Province.
He said he was hired by a stranger to deliver drugs from Laos to a parner in Vietnam.
A phone was among the evidence seized by authorities.
Laos police have taken over the investigation.
Vietnam is a key trafficking hub for drugs in and around the "Golden Triangle," a lawless wedge of land that intersects China, Laos, Thailand and Myanmar and is the world's second largest drug producing region.
Drug busts and convictions have been reported in Vietnam almost every week, despite the country having very tough drug laws. Smuggling, trading and producing drugs all face death sentence.