It is Vietnam's first gold in the quad event after losing to Thailand numerous times in the past.
In the final played in Bangkok, they won 21-15, 23-21.
Tran Thi Ngoc Yen, a member of the team, said as a kid she had seen Vietnam lose frequently to Thailand and this provided motivation for her to win the final.
"We have succeeded in defeating Thailand. This joy cannot be described in words."
Vietnam dominated the event, winning all three group matches, including a 21-0, 21-0 defeat of Pakistan, and beating South Korea in the semifinals.
The 35th edition of the King's Cup Sepaktakraw World Championship is being held from July 23 to 31.
On Thursday afternoon the Vietnamese women play South Korea in the final of the regu event.