The track logs a third week at the summit, fending off competition from Guy Sebastian's 'Battle Scars', which rebounds three to two.
Meanwhile, Birdy's 'Skinny Love' lifts five to three, Adele lands at five with 'Skyfall', and Ke$ha jumps 11 to ten with 'Die Young'.
Further down the chart, Sam and the Womp leap 17 to 12 with 'Bom Bom', Swedish House Mafia vault 25 to 13 with 'Don't You Worry Child', and Pitbull's 'Don't Stop The Party' bounds 23 to 15.
Bruno Mars starts at 20 with 'Locked Out Of Heaven', Taylor Swift's 'I Knew You Were Trouble' is new at 24, and Reece Mastin debuts at 31 with 'Rock Star'.
Elsewhere, Of Monsters and Men climb from 44 to 34 with 'Little Talks', and Mumford & Sons bow at 40 with 'I Will Wait'.
The top ten singles appear below (click for our reviews where possible):
1. (1) Psy: 'Gangnam Style'
2. (3) Guy Sebastian ft. Lupe Fiasco: 'Battle Scars'
3. (5) Birdy: 'Skinny Love'
4. (4) The Script ft. will.i.am: 'Hall of Fame'
5. (*) Adele: 'Skyfall'
6. (9) Pink: 'Try'
7. (2) One Direction: 'Live While We're Young'
8. (8) Rihanna: 'Diamonds'
9. (6) Flo Rida: 'I Cry'
10. (11) Ke$ha: 'Die Young'
Watch Psy's 'Gangnam Style' video below: