Tan Son Nhat placed sixth with 2.44 million departing seats, up 11.4% year-on-year, followed by Noi Bai in seventh with 2.06 million, an increase of 13% from last year.
In recent years, Vietnam's two largest airports have upgraded infrastructure and improved service quality.
In May, Tan Son Nhat inaugurated its T3 domestic terminal, designed to handle 20 million passengers annually and about 7,000 passengers per hour.
Singapore's Changi Airport was the busiest in Southeast Asia in August, followed by Kuala Lumpur International Airport in Malaysia and Jakarta Soekarno-Hatta Airport in Indonesia.