Ho Chi Minh City Police said they had arrested at least six members of an illegal gambling ring on Thursday just before it could process hundreds of millions of dollars in bets on the World Cup final.
Many others were summoned to the police station for their roles in the ring.
According to authorities, the ring (rooted in Phillippines) has lured thousands of Vietnamese gamblers to place online bets at 166bet.net.
Police raided the website's eleven locations in the Ho Chi Minh city right after the end of the World Cup final between Argentina and Germany finished early on July 14.
Dozens of gamblers placing cash bets were arrested at the scene.
A numerous of bank cards, hard drives, laptops and other evidence was seized in the raid.
Gambling transactions via the website during the single World Cup football match reached a total of VND 200 billion (US$9.4 million).
Gambling is illegal in Vietnam. On July 9, police announced that they had busted an 11-person online gambling ring which had allegedly processed VND5 trillion ($235 million) in Thanh Hoa Province.
On July 4, a task force from the Ministry of Public Security busted another gambling ring operating on M88.com. More than VND 1.4 trillion ($66 million) was seized from the site's account, police said.