The rapper spends a second week at the summit and holds off fierce competition from One Direction, who debut at two with 'Live While We're Young'.
Elsewhere in the top ten, Rihanna's 'Diamonds' lands at number eight, Pink's 'Try' rebounds 11 to nine, and Rita Ora holds at ten with 'R.I.P'.
Meanwhile, Ke$ha lands at 11 with 'Die Young', David Guetta's 'Play Hard' with Akon and Ne-Yo leaps 24 to 16, and Sam and the Womp's 'Bom Bom' vaults 27 to 17.
Pitbull enters at 23 with 'Don't Stop The Party', Taylor Swift's 'Red' is at 30, and Labrinth is new at 33 with 'Treatment'.
Further down the chart, Nicki Minaj begins at 36 with 'Va Va Voom', The Temper Trap re-enter at 38 with 'Trembling Hands', while their 'Sweet Disposition' rebounds at 50.
The top ten singles appear below (click for our reviews where possible):
1. (1) Psy: 'Gangnam Style'
2. (*) One Direction: 'Live While We're Young'
3. (2) Guy Sebastian ft. Lupe Fiasco: 'Battle Scars'
4. (5) The Script ft. will.i.am: 'Hall of Fame'
5. (3) Birdy: 'Skinny Love'
6. (4) Flo Rida: 'I Cry'
7. (6) Taylor Swift: 'We Are Never Ever Getting Back Together'
8. (*) Rihanna: 'Diamonds'
9. (11) Pink: 'Try'
10. (10) Rita Ora ft. Tinie Tempah: 'R.I.P'
Watch Psy's 'Gangnam Style' video below: