The track, which the singer rush-released worldwide last week, marks her third number one on the Australian tally.
Her previous chart toppers were 'Just Dance' and 'Poker Face' in 2008.
Meanwhile, last week's chart leader Rhianna slips to second place with 'S&M', while The Black Eyed Peas's 'Just Can't Get Enough' completes the top three.
Elsewhere in the top ten, Alexis Jordan remains at five with 'Happiness', and Avril Lavigne advances from eight to six with 'What The Hell'.
Further down the chart, the Glee Cast land at 17 with 'Thriller/Heads Will Roll', Ke$ha debuts at 24 with 'Blow' and Lady Antebellum's 'Need You Now' re-enters at 31.
The top ten singles in full (click where possible for our reviews):
1. (*) Lady GaGa: 'Born This Way'
2. (1) Rihanna: 'S&M'
3. (3) The Black Eyed Peas: 'Just Can't Get Enough'
4. (2) Wynter Gordon: 'Dirty Talk'
5. (4) Alexis Jordan: 'Happiness'
6. (8) Avril Lavigne: 'What The Hell'
7. (7) Usher: 'More'
8. (6) Katy Perry: 'E.T'
9. (4) Enrique Iglesias ft. Ludacris & DJ Frank E: 'Tonight (I'm Lovin' You)'
10. (9) Chris Brown: 'Yeah 3X'