The list, which aims to showcase the best new acts for the year ahead, was compiled using tips from 213 UK-based critics, broadcasters and bloggers.
Now in its 11th year, previous winners include Michael Kiwanuka, Jessie J, Adele, Mika, Ellie Goulding and Keane. BBC Radio 1 DJ Huw Stephens said Haim had a "contagious enthusiasm".
"Haim have an unapologetic passion for music
that shines in their songs," he said. "They're brilliant musicians who
have a real talent for tunes that merge their tales of growing up in the
21st Century with a classic songwriting ability."
Este, Danielle and Alana Haim, who are aged between 21 and 26, started playing music as children when their parents enlisted them into a family covers band.
The sisters all play guitar, drums and sing and are still occasionally known to pull their mother and father on stage.
Haim's songs pay homage to feelgood, freewheeling '70s rock and anthemic '80s synth-pop, gaining a modern sheen by borrowing rhythms from contemporary R&B.
The 213 tastemakers - ranging from music magazine editors and newspaper critics to influential bloggers, DJs and radio and TV producers - each named their favourite three new acts.
They were free to choose performers from any country and any musical genre.
Artists who had scored a UK top 20 single or album before 11 November 2012 were ineligible, as were those already well-known to the UK public - for example by featuring in the final stages of a TV talent show or already being a member of a successful band.
The tips were compiled into a longlist of the
top 15 artists, which was published in December, and the top five have
been revealed this week.
It is the first time that the top five acts have all been female or fronted by women.
Este Haim said: "It's the craziest thing to think we're on a list with so many amazing artists. This year the five bands that were in the list were all female fronted, right?
"We love the UK - the last time we were there, we were there for almost a month and a half. The UK is like a second home."
NME magazine's new music editor Matt Wilkinson, who took part in the poll, said Haim "have a knack for writing amazingly catchy singles, they're a killer live band and they talk the talk miles better than most other new bands".
"It's a rare and exciting combination," he added.
Michael Kiwanuka was top of the Sound of 2012 list. The London troubadour sold 500,000 copies of his debut album Home Again around the world last year and was nominated for the Mercury Prize.
The other previous winners are: Jessie J (Sound of 2011), Ellie Goulding (Sound of 2010), Little Boots (Sound of 2009), Adele (Sound of 2008), Mika (Sound of 2007), Corinne Bailey Rae (Sound of 2006), The Bravery (Sound of 2005), Keane (Sound of 2004) and 50 Cent (Sound of 2003).
Other artists in the top five in previous years include Frank Ocean (Sound of 2012), The Vaccines (Sound of 2011), Marina and the Diamonds (Sound of 2010), Florence and the Machine (Sound of 2009), Foals (Sound of 2008) and Plan B (Sound of 2006).
One of their songs:
source: cnn.com
