The group hold off competition from Young Money, who climbs one place to two with 'Bed Rock'.
Rihanna jumps 15 to eight with 'Rude Boy', the third single from her Rated R album to enter the top 10.
Elsewhere, Lady GaGa's 'Telephone' rises a further two places to 12 and The Script's 'Breakeven' continues its steady climb, going up three to 19.
The highest new entry comes from Ludacris, who debuts at 46 with his Nicki Minaj collaboration 'My Chick Bad'.
Taio Cruz's 'Break Your Heart', which recently topped the US iTunes chart, enters the countdown at 53.
The top ten singles in full (click for our reviews):
1. (1) Black Eyed Peas: 'Imma Be'
2. (3) Young Money: 'BedRock'
3. (5) Lady Antebellum: 'Need You Now'
4. (2) Ke$ha: 'Tik Tok'
5. (4) Lady GaGa: 'Bad Romance'
6. (7) Train: 'Hey, Soul Sister'
7. (8) Ludacris: 'How Low'
8. (23) Rihanna: 'Rude Boy'
9. (10) Trey Songz: 'Say Aah'
10. (9) Jason Derulo: 'In My Head'