Their combined sales grew 37% to US$4.07 billion, accounting for around 2.8% of country's total retail sales, the ministry's Vietnam E-commerce and Information Technology Agency said. The sales were forecast to hit US$10 billion in the next five years.
The report covered all companies with websites that allow visitors to buy products and services, not just online retailers à la Amazon.
Biggest earners included Lazada, a subsidiary of Germany's Rocket Internet, platform chodientu, and discount website Hotdeal. Vietnam Airlines and The Gioi Di Dong (Mobileworld) was also named among businesses with strong online sales.
Around 62% of Internet users in Vietnam did online shopping last year, compared to 58% in 2014, according to the agency, which conducted a survey among nearly 970 Internet users around the country.
Each online shopper spent an average of US$160, compared to US$145 in the year before, the agency said. With the population of 91.3 million, Vietnam's Internet penetration was last estimated at 45%.
Clothes, footwear and cosmetics were the most popular among Vietnamese online shoppers, followed by electronics and digital devices.
Despite their increased engagement in online shopping, 91% of the interviewed shoppers paid their online orders in cash, the agency said.
Less than half of them transferred money via bank accounts, while 20% used credit cards.