The goal came in the second half following a penalty scored by Nhat Nam in the 47th minute.
The 1-0 lead was then maintained to the end of the game. The Vietnamese footballers will play another friendly match against hosts Tajikistan which is due to take place on March 23.
The AFC U23 Asian Cup's final round is scheduled to take place in Qatar from April 15 to May 3, with Vietnam playing in Group D alongside Uzbekistan, Kuwait, and Malaysia.
In Qatar, the four teams will compete in a round-robin format in the group stage, with the two strongest teams then advancing to the quarter-final stage.
Uzbekistan are theoretically considered to be the strongest team because they have regularly recorded strong results at continental youth tournaments over recent years.
The AFC U23 Cup finals will also serve as a qualifier for the 2024 Olympics which will be held in France this summer.
The top three finishers will qualify for the Paris Olympics, while the fourth-placed team will participate in a playoff against an opponent from the Confederation of African Football (CAF) for a chance to compete at the tournament.
VOV