A header by Van Tung and a close-range finish by Quoc Viet put Vietnam at second place in Group B after Thailand.
"I am satisfied with Vietnam’s victory today. We scored two goals and did not concede any," coach Philippe Troussier told reporters after the match.
"It was great to start with a win, but of course I was not happy at some moments when the players could have done better."
Vietnam are now in a good position for the next three matches to aim for either the first or second place in Group B ranking, he added.
Vietnam will play Singapore on Wednesday.
Source: VOV5