Olivier Giroud fired the Gunners into a fifth-minute lead before doubling their advantage with a curled effort on 43 minutes.
The Frenchman had time to seal his hat-trick before the break thanks to a dinked finish over the goalkeeper.
It was 4-0 early in the second half when Alex Oxlade-Chamberlain swept the ball home confidently.
The goals continued to flow for Arsenal as Chuba Akpom found the bottom corner, while the youngster grabbed a second in the 58th minute with a simple strike.
The visitors then scored their seventh of the match 15 minutes from time through Ignasi Miquel.
Vietnam managed to get on the scoreboard soon after as Tran Manh Dung saw his effort loop fortuitously into the net.
However, the home side ended the match with 10 men after goalkeeper Tran Buu Ngoc was shown a red card for handling outside of the penalty area.