Seven players finished on the scoresheet and captain Cho So-Hyun got a hat-trick as the Koreans, already 7-0 up at half-time, poured on another five goals in the second half.
And it was not the tournament's only big scoreline as eight-time champions China smashed Thailand 7-0 in the later game in Vietnam's Ho Chi Minh City.
Myanmar's coach Yoshinori Kumada said his team were simply unable to match the strong Korean side in difficult conditions.
"We planned systems in training and worked out strategies but they were not matched in the performance today," he said, according to the Asian Football Confederation website.
"The opponents were a very strong team that we couldn't handle and the wet pitch and humid conditions were difficult for my players to cope with. However, we have no excuses today for what was a poor performance by the side."
For China, Korea Republic's main rivals in Group B, striker Yang Li scored twice in each half in another result which went beyond emphatic at Thong Nhat Stadium.