More than two-thirds of the 650 victims at Regina Miracle International Vietnam, a Hong Kong-owned garment factory that manufactures lingerie for labels including Victoria's Secret, were sent to hospital.
Most of them suffered from dizziness, stomach pain and headaches after eating lunch at the canteen in in Hai Phong, a city 60km from Hanoi.
Authorities have been investigating the cause of the outbreak and closed the canteen temporarily.
Food poisoning outbreaks, especially those taking place in factory canteens, have become increasingly common in Vietnam.
A report by the health ministry's food safety department has shown that in the last four years, more than 6,000 people have been hospitalised in 84 food poisoning cases that occurred at canteens in industrial zones and export processing zones.
Further official statistics revealed that more than 380 people across the country suffered from food poisoning in October alone, when food safety authorities conducted an investigation into the issue.
They found that 68% of cases occurred at public canteens in industrial zones, with most of these originating from food suppliers who did not ensure food hygiene and safety during production and processing, according to Administration for Food Safety and Hygiene director Nguyen Thanh Phong.
Phong found that nearly 20% of the contract meal providers were not certified for food safety, with around 16% failing to meet hygiene regulations and nearly 10% found to be using unidentified ingredients.