Ho A Ran, 32, Ho A Khay, 26, and Ho Van Long, 22, got death sentence while Ho A Liem, 25, received life imprisonment, as decided by the court of Quang Tri Province on Wednesday.
The four, who are all residents of Quang Tri's Huong Hoa District, are charged with "illegal transportation of narcotic substances."
According to the verdict, Ran received a package of meth from a strange man on the Quang Tri border between Vietnam and Laos on Aug. 13, 2021.
Later, he divided the meth into small packages and gave them to Long, Liem and Khay for delivery to Huong Hoa District.
Long was arrested en route while the other three later turned themselves in.
Police seized the entire six-kilogram meth haul.
Vietnam has been identified by security agencies as a key trafficking hub for narcotics despite having some of the world's toughest drug laws.
Those convicted of possessing or smuggling more than 600 grams of heroin or more than 2.5 kilograms of meth face the death penalty.