The duo held off competition from new Top 10 entries by David Guetta, Jessie J and Aloe Blacc, with the song now having shifted over 400,000 sales since its release.
David Guetta's 'Where Them Girls At?', featuring Flo Rida and NIcki Minaj, entered the chart at number three, marking the producer's 12th top 20 release and his second current Top 10 song, with Snoop Dogg featuring David Guetta at number five with 'Sweat'.
BBC Sound of 2011 winner Jessie J earns her third Top 10 hit, as 'Nobody's Perfect' climbs from 18 to number nine, after 'Do It Like A Dude', which reached number two late last year, and its number one follow-up 'Price Tag'.
Katy Perry and Kanye West, and Wretch 32 featuring Example both fall one place, with 'E.T.' and 'Unorthodox' sitting at six and seven respectively.
US soul singer Aloe Blacc, meanwhile, rises from number 15 to number 10 with 'I Need A Dollar' after eight weeks on the chart.
Sliding down the chart, Tracy Chapman's 'Fast Car' falls from nine to 13, while last week's new entry 'Guilt' by Nero drops seven places to 15.
Elsewhere in the chart, Beyonce falls eight to 19 with 'Run The World (Girls)' and Black Eyed Peas drop to 18 with 'Just Can't Get Enough', while Lady GaGa climbs three from 23 to break back into the top 20 with 'Judas'.
The Top 10 singles in full:
1. (1) LMFAO ft Lauren Bennet & Goonrock: 'Party Rock Anthem'
2. (2) Bruno Mars: 'The Lazy Song'
3. (-) David Guetta ft. Nicki Minaj & Flo Rida: 'Where Them Girls At?'
4. (4) Chris Brown ft. Benny Benassi: 'Beautiful People'
5. (3) Jennifer Lopez ft. Pitbull: 'On The Floor'
6. (5) Snoop Dogg ft. David Guetta: 'Sweat'
7. (6) Katy Perry ft. Kanye West: 'E.T.'
8. (7) Wretch 32 ft. Example: 'Unorthodox'
9. (18) Jessie J: 'Nobody's Perfect'
10. (15) Aloe Blacc: 'I Need A Dollar'
Source: Official Charts Company
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