The Dublin-born brothers, who first topped the chart two weeks ago, knock Simon Cowell's Haiti charity single to second position following its one-week reign at the summit.
Owl City's 'Fireflies' remains in third place, while Timbaland and Katy Perry's 'If We Ever Meet Again' and the Glee cast's release 'Halo/Walking On Sunshine' make up the rest of the top five.
Meanwhile, supergroup Artists For Haiti - who include Nicole Scherzinger and Janet Jackson - provide the highest new entry of the week with their charity single 'We Are The World 25 For Haiti' debuting in ninth spot.
The top ten singles in full (click where possible for our reviews):
1. (2) Jedward ft. Vanilla Ice: 'Under Pressure (Ice Ice Baby)'
2. (1) Helping Haiti: 'Everybody Hurts'
3. (3) Owl City: 'Fireflies'
4. (5) Timbaland ft. Katy Perry: 'If We Ever Meet Again'
5. (4) Glee Cast: 'Halo/Walking On Sunshine'
6. (7) Glee Cast: 'It's My Life/Confessions, Pt. II'
7. (8) Lady GaGa: 'Bad Romance'
8. (18) Alicia Keys: 'Empire State Of Mind (Part II) Broken Down'
9. (-) Artists For Haiti: 'We Are The World 25 For Haiti'
10. (9) Iyaz: 'Replay'