Venezuela's Dayana Mendoza, 22, burst into tears when the presenter, US talk show host Jerry Springer, announced she had beaten finalists from Colombia, the Dominican Republic, Mexico and Russia.
The 178-centimetre (five foot 10) beauty, the favourite of pageant bloggers and online bookmakers, clinched the diamond-studded gold crown after answering a question on the difference between men and women.
"Men think that the fastest way to go to a point is to go straight," explained the trilingual aspiring interior designer. "Women know that the faster way to go to a point is to go to the curves."
Mendoza, who was once kidnapped in her home country, later issued a call for an end to violence in the world.
"The kidnapping happened a year and a half ago," she said at a post-pageant press conference, answering questions in both English and Spanish.
"It's something that happens in my country. You don't even have to have money to be kidnapped ... That's why I wanted to raise my voice and tell the world that violence is not the answer."Asked how she felt during the pageant and what she would do next, the green-eyed brunette said she had said a series of prayers seconds before her victory, and quipped that she would now "go home and take off my shoes."
Her prize package includes cash, a year-long contract promoting Miss Universe, world travel, a rent-free New York City luxury apartment and a giftbag stuffed with free designer shoes, dresses and beauty products.
In the world of beauty contests, Venezuela -- where such contests are held in schools, villages and even prisons -- is considered a "pageant superpower" with four previous Miss Universe and five Miss World winners.
Kicking off the extravaganza, ex-"Spice Girl" Mel B shouted "Good Morning, Vietnam!" -- an apt greeting since the final was held at 8:00 am local time to coincide with prime-time Sunday evening TV slots in the Americas.
The 80 contestants were introduced in their national costumes, with Miss New Zealand sporting a Maori-style pretend-facial tattoo, Miss Korea twirling a martial arts sword and Miss Albania dazzling in a vampire theme.
Heartbreak came quickly for 65 of the beauties when the 15 semi-finalists were announced, a list chosen last week but kept highly classified by the event group, co-owned by US millionaire Donald Trump.
Also on the shortlist were the contestants from Kosovo -- represented for the first time -- and Australia, the Czech Republic, Hungary, Italy, Japan, South Africa, Spain, USA and Vietnam.
A jury, including high-profile fashionistas and Donald Trump Junior, quickly thinned out their ranks to 10, based on how they negotiated the runway in skimpy bikinis, and what Mel B called the "wow factor."
Vietnam home girl Nguyen Thuy Lam was eliminated at this stage, to the dismay of local fans who had paid up to 1,800 dollars for tickets to the event held at the 7,500-seat Crown Convention Centre in Nha Trang.
Next came the evening gown section, a pageant minefield in which women must avoid tripping -- which is exactly what happened to 26-year-old Crystle Stewart, the second Miss USA in consecutive years to take a fall.
Vietnam, the first communist nation to host the pageant, was promoted heavily as a tourist destination during the two-hour show seen in 170 countries -- and Mendoza said a month-long stay here had worked its magic on her.
"When we were young we studied and we saw Vietnam as a country with wars and troubles," she said.
"But once I got here, I realised that it's just like being in Venezuela. It doesn't matter what happens, you always have a reason for smiling. We share the same will to be great countries. I like it, I love it."