The Vietnamese government says 186,000 homes have been damaged across the country, with more than three million livestock swept away. Officials estimate there has been hundreds of millions of pounds worth of damage.
The mountainous province of Dak Lak has been severely impacted, recording more than 60 deaths since 16 November, according to news agency AFP.
The floods are the latest extreme weather event to hit Vietnam in recent months, after typhoons Kalmaegi and Bualoi hit the country within weeks of each other.
Some 258,000 people were without power on Sunday morning and sections of major motorways and train tracks were blocked, officials said.
Military and police resources have been mobilised to assist in the hardest hit areas.
The government said the most severe impacts had been observed in five provinces - Quang Ngai, Gia Lai, Dak Lak, Khanh Hoa, and Lam Dong - clustered in south and south-central Vietnam.
Mach Van Si, a farmer in Dak Lak, told AFP: "Our neighbourhood was completely destroyed. Nothing was left. Everything was covered in mud."
Prime Minister Phạm Minh Chính chaired a virtual emergency meeting on Sunday morning from South Africa, where he had been attending the G20 summit.
Rainfall had exceeded 1.5m (5ft) in several areas leading up to Friday, with some areas surpassing a 5.2m level not seen since 1993. The rain is forecast to ease in the coming days.
Scientists say that Vietnam has been left more exposed to extreme weather events by human-driven climate change, which has made typhoons stronger and more frequent.
