After a see-saw first set in which the Thai team edged second-seeded Japan 25-22, the Thais never looked back. They easily won the second and third sets 25-18 and 25-17 in a raucous Chatchai Hall.
It was the best performance of the tournament for the Thai side, which appeared to improve with every match following a shocking loss in the Sept 13 opener to Kazakhstan 24-26, 24-26, 25-17 and 20-25.
In the third-place match earlier on Saturday, South Korea defeated top seed China in five sets.
Massive crowds formed a two-kilometre queue on a rainy Saturday morning to get tickets for the final featuring a Thai side ranked 16th in the world.
An estimated 10,000 fans packed the grounds in front of the 5,000-seat Chatchai Hall and had spilled onto the main road for almost two kilometres by the time tickets went on sale at 9am.
Each person was entitled to purchase only one ticket and not allowed to buy tickets for other people in order to ensure fairness.
The tickets cost 100 and 200 baht, but scalpers were asking 1,000 to 2,000 baht after the hall sold out, reports said.
Police officers were deployed to maintain order and prevent possible crimes.
The excessive number of spectators prompted the organisers to sell an additional 400 standing-room tickets. They were priced at 100 baht each and distributed to people through a drawing of lots early in the afternoon.
As well, the dome on the stadium premises had televisions and giant projection screens to allow people who missed out on tickets to watch the match there.
A Facebook page called "Thailand Volleyball" reported that a man had travelled from Samut Prakan and was seen camping out in front of the hall at 2am, waiting to buy a ticket. Some media reports said another group of fans had waited outside the stadium since 10pm Friday.
The Thai team on Friday pulled off a brilliant 3-2 win against defending champions China to reach the final after coming from behind to stun the 12-time Asian champions 19-25, 25-19, 25-22, 21-25,16-14.
Thailand had upset Japan in an earlier contest on Monday. The Thais stunned the 2012 Olympic bronze medallists 25-15, 25-23, 23-25, 30-28 in their first win over the three-time Asian champions this year after defeats at the World Grand Prix in Turkey and this month's World Championship qualifying tournament in Japan.
Thailand qualified for the World Championship next year in Italy by virtue of its performance in Japan.
Japan came to the Asian final by beating South Korea 25-22, 19-25, 25-19, 25-20 in another semi-final on Friday. The Japanese were in their second straight final after losing to China in the 2011 showdown.
The Thais have won only one Asian title in 2009 when they defeated the Chinese in the final. They finished fourth two years ago after being defeated by South Korea 22-25, 26-24, 23-25, 27-25 and 15-13 in a five-set thriller.