Hanoi got the Prime Minister's nod, chosen ahead of Ho Chi Minh City by virtue of its proposal costing much less, and its existing infrastructure and previous experience in hosting several huge sporting events.
The event will take place between October and December in 2021.
The decision on Hanoi came after the SEA Games Federation (SEAGF) informed it would hand over hosting rights for the 31st edition of the SEA Games to Vietnam, because Cambodia, the original host, said it was not ready yet.
Vietnam was originally scheduled to host the 32nd edition of the biennial event in 2023.
The Ministry of Sports, Culture and Tourism said Hanoi meets all the requirements of infrastructure and human sources to organize the large-scale event, and has previous experience, having hosted the games in 2003.
In 2016, Hanoi had submitted a VND1.7 trillion ($74.8 million) budget proposal for the event, while HCMC submitted a VND15.6 trillion budget for the event this January.
The SEA Games are held every two years. When Vietnam hosted the Games in 2003, the main events were held in Hanoi and some in HCMC. Last year, the country sent 476 athletes to the Games in Kuala Lumpur, which gathered around 6,000 athletes from 11 Southeast Asian states.
The upcoming edition of SEA Games will take place in Metro Manila, the Philippines in 2019.