Madonna and Justin Timberlake's '4 Minutes' and Flo Rida ft. T-Pain's 'Low' are also non-movers at two and three respectively.
Former American Idol winner Jordin Sparks leaps 11 places to five with Chris Brown collaboration 'No Air', while Rihanna climbs three to enter the chart at ten with 'Take A Bow'.
Elsewhere, Leona Lewis falls three to nine with 'Better In Time'.
The top ten singles in full:
1. (1) Gabriella Cilmi: ‘Sweet About Me’
2. (2) Madonna ft. Justin Timberlake: '4 Minutes'
3. (3) Flo Rida ft. T-Pain: 'Low'
4. (7) Estelle ft. Kanye West: 'American Boy'
5. (16) Jordin Sparks and Chris Brown: 'No Air'
6. (5) Newton Faulkner: 'Dream Catch Me'
7. (9) Vanessa Amorosi: 'Perfect'
8. (8) Usher ft. Young Jeezy: 'Love In This Club'
9. (6) Leona Lewis: 'Better In Time'
10. (13) Rihanna: 'Take A Bow'.