Judges, including rock star Steven Tyler from Aerosmith, picked the winner from a total of 86 contestants at the show, watched by millions of viewers around the world. (Agencies)
Last year's winner Olivia Culpo of the United States placed a diamond crown on the head of Isler, who wore a silver rhine-stone studded evening dress.
Isler's triumph was the seventh Miss Universe win for Venezuela, where beauty pageants are a major source of national pride.
After the show, she beamed and waved to journalists, wearing the Miss Universe sash and standing next to the show's owner, US tycoon Donald Trump.
"I feel a lot of emotions," she said.
"I'm still in shock. I feel so blessed, so happy to be here."
"It's been a lot of fun and a great success," said Trump.
In the decisive interview round that concludes the competition, Tyler asked Isler, who won Miss Venezuela last year, what her greatest fear was.
She did not give any details, but said: "I believe we should overcome all our fears and this in turn will make us stronger."
Isler is now set to pose today in a specially created jewelled swimsuit that the organizers said was worth USD1 million.
The previous Miss Universe, Culpo, earlier appeared on stage wearing the white cutaway swimsuit studded with diamonds, rubies and emeralds.
"That swimsuit travels with an armed security guard 24/7," commented co-host Thomas Roberts, an American television presenter.
Roberts, who co-hosted the final with ex-Spice Girl Melanie Brown, dedicated the show to the people suffering from the typhoon in the Philippines.
"We send our very best, our thoughts. We dedicate tonight's show to you," he said.
The presenters greeted the audience in unison in Russian: "Privet!" or hi.
The show included a performance by Tyler, who sang "Dream on, dream until your dream comes true," while standing on top of a white grand piano.
All 86 contestants initially appeared on stage in red and black cocktail dresses. They then changed into red and black bikinis.
The judges then whittled down the contestants to a final 16, who faced off in a bikini round, carrying white fur stoles.
Then a final 10 women strutted on the stage in elaborate sequinned evening gowns, before the final five answered questions in the interview round.
Judges, including rock star Steven Tyler from Aerosmith, picked the winner from a total of 86 contestants at the show, watched by millions of viewers around the world.