The soul singer held off competition from 'Just The Way You Are' by Bruno Mars and dancefloor favourite 'Barbra Streisand' by Duck Sauce, to notch up a second week at number one.
This week's second-highest new entry is reigning X Factor champ Joe McElderry, whose sophomore track 'Ambitions' lands at six.
The top ten is rounded out this week by two massive climbers, Mike Posner's 'Cooler Than Me', which advances 13 places from 22 to nine, and Usher's 'DJ Got Us Fallin' In Love', which rises from 18 to ten.
Elsewhere, seven tracks between positions 11 and 20 fall down the chart, the biggest tumbler being Adele's 'Make Me Feel Your Love', which slips nine places from 11 to 20.
The top 20 also sees Travie McCoy's 'Billionaire' jump from 15 to 11, while two new entries - Pixie Lott's 'Broken Arrow' and Michael Bublé's 'Hollywood' - arrive at 12 and 17 respectively.
The top 10 in full:
1. (1) Cee Lo Green: 'Forget You'
2. (4) Bruno Mars: 'Just The Way You Are'
3. (-) Duck Sauce: 'Barbra Streisand'
4. (5) Swedish House Mafia Vs Tinie Tempah: 'Miami 2 Ibiza'
5. (3) Tinie Tempah: 'Written In The Stars'
6. (-) Joe McElderry: 'Ambitions'
7. (2) Robbie Williams & Gary Barlow: 'Shame'
8. (6) Labrinth: 'Sunshine'
9. (22) Mike Posner: 'Cooler Than Me'
10. (18) Usher ft. Pitbull: 'DJ Got Us Fallin' In Love'
Source: Official Charts Company
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