WPP had placed advertisements of two brands in the movie "Flight to you," which was broadcast on YouTube on includes the U-shaped line, the Department of Broadcasting, Television and Electronic Information under the ministry said.
China has used the U-shaped line to claim most of the South China Sea and illegally parts of maritime Vietnam. The claim has been internationally rejected and condemned.
WPP also advertised three cosmetics products on YouTube that did not suit its permits, the department said.
The company was fined a total of VND55 million (US$2,160) on Wednesday and ordered to remove the violating ads.
WPP said it has adopted different measures to prevent advertisements from being attached to illegal content, but has not managed to stop all cases given shortcomings with YouTube algorithms.
The company said it will actively join the information ministry's "white list" initiative to ensure brand safety.
The information ministry has published a black list of pages with toxic content that companies should not partner with, and a white list of verified pages.
