Host and late-night comedian Conan O'Brien kicked off the unbuttoned awards on Sunday by trying to break the record for the most celebrity cameos in his intro, notching up 50. Among them were Taylor Swift, who gave him a manicure, and Internet sensation Grumpy Cat, who slept in the front row of the audience.
Hill won best comedic performance for his role as the drug-addled swindling stockbroker in director Martin Scorsese's "The Wolf of Wall Street," a role for which he was nominated for the Oscar for best supporting actor.
"I want to thank my hero Martin Scorsese, my favorite person of all time," said Hill, upon receiving MTV's award in the shape of a movie popcorn bucket.
Leto won best on-screen transformation for his role as a transgender woman in "Dallas Buyers Club," a role for which he won the best supporting actor Oscar.
Zac Efron took one of the audience's favorite awards of the night, best shirtless performance for "That Awkward Moment," and eventually took off his shirt with help from singer Rita Ora as he accepted the award.
Actress Mila Kunis won best villain for her role as Theodora, Wicked Witch of the West in "Oz The Great and Powerful."
Voters select the winners online and voting for the top award of the night, movie of the year, continued during the show.
The big losers on Oscar night "The Wolf of Wall Street" and "American Hustle" led nominees for the awards, eaching landing eight nods.
The MTV Trailblazer Award went to actor Channing Tatum for his versatility in playing everything from a dancer from the wrong side of the tracks to a hero trying to save the world from danger.
Mark Wahlberg, who most recently starred in the Afghanistan war drama "Lone Survivor, will receive this year's MTV Generation Award, an honor given to those who engage with the MTV audience throughout their careers.
(Reporting By Mary Milliken; Editing by Simon Cameron-Moore)