The 22-year-old played five songs, including Only Girl (In The World) and Cheers, which she dedicated to "all the semi-alcoholics in the world".
Rihanna said the album had been recorded late at night after she came off stage on her Last Girl On Earth world tour.
"I'd be doing vocals at 4am with a raspy voice," she joked.
The record, Rihanna's fifth in six years, marks a return to the singer's pop roots after the bleak nihilism of last year's Rated R.
That album, recorded in the wake of the star's assault by then-boyfriend Chris Brown, had a much darker tone - presaged by single Russian Roulette, which talked about a subservient, violent relationship.
One track from the new album, S&M, revisits those themes, with Rihanna declaring, "sticks and stones may break my bones, but whips and chains excite me".
But most of the new material presented a more carefree side to the Barbadian star.
Fizzing synths, club beats and sing-along chants featured heavily, with three songs - Only Girl, What's My Name and S&M - produced by Norwegian team Stargate.
The duo previously collaborated with Rihanna on dance tracks like Don't Stop The Music and Rude Boy.
Cheers, which the singer also referred to by its working title, Drink It Up, was a funky, loping guitar groove dedicated to a night on the town.
Despite its lyrical content, Rihanna confessed she was "too busy" to drink alcohol, and "hardly ever gets any sleep".
The night concluded with a strummed, acoustic ballad called California King Bed, about a couple who sleep beside each other but feel "10,000 miles apart".
Dressed in a figure-hugging white dress with a bold floral print, Rihanna sang along while her new music played, and chatted bashfully to a small audience of invited fans and journalists.
She revealed that the new album would also contain a duet with R&B star Drake and a collaboration with hotly-tipped rapper Nicki Minaj on a track called Raining Men.
"Thanks for coming along tonight, this really means a lot to me," she said. "Thank you for coming to hear my silly music."
Loud is due for release in the UK in November.

There are currently 18 teams in the top two tiers of the WSL, which is being increased to 20 clubs by the year 2017.
"Where we really want to get to is 24 fully-professional women's teams playing in the league," Brazier told BBC Radio 5 live sports extra.
"But we need to do that slowly, so the clubs can become sustainable."
Sheffield became the first team to be promoted to WSL Two when they beat Portsmouth in the Premier League play-off final, having also met the WSL's licensing requirements.
In addition to being able to prove their financial solvency, clubs applying for entry to the Super League must show they will attract an average of 350 spectators in 2016, increasing to at least 400 in 2017.
"We have a licence system within the WSL and the reason for that is to try and influence and shape the way that money is invested into the game and do it slowly, in a measured way," Brazier added.
"By having a salary cap in place, it means that we can also ensure that money is invested off the pitch, as well as on the pitch, in salaries.
"Building things slowly is really important, because we want it to be sustainable."
Pop star Rihanna has unveiled tracks from her forthcoming album, Loud, at a club in London.
[NEXT_CONCEPT]
The Women's Super League could be expanded to 24 teams in the future, according to the FA's head of women's competitions, Katie Brazier.