Model Thai Ha was fined VND5 million (US$250) for undue exposure of her breasts while performing in a show called the Umbrella Party in Ho Chi Minh City on February 18.
The show was held to promote a new AXE brand body spray for males.
Photographs featuring Ha's partially exposed breasts spread quickly on the Internet.
Ha apologized to her fans saying the exposure, which happened while she was dancing, was "an inadvertent moment" that occurred because the costume did not fit her very well.
She became the first local artist to be fined by the Department of Culture, Sport and Tourism this year for indecent exposure at art and cultural events.
Thai Ha, born in 1987, represented Vietnam at Miss International Tourism 2009 and is ranked as one of the top models in the country.