The singer previously reached the top with 'Lady Marmalade', a 2001 collaboration with Christina Aguilera, Lil' Kim and Mya.
Last week's number one, 'Whatever You Like' by rapper T.I., slips to second, while Rihanna holds steady in third with 'Disturbia'.
The highest new entry of the week comes from T.I. and Jay-Z, who bow at five with 'Swagga Like Us', a rap single that also features appearances from Kanye West and Lil Wayne.
Meanwhile, British rapper Estelle enters the US top ten for the first time, climbing to nine with her UK number one single 'American Boy'.
The top ten in full (click where possible for our reviews):
1. (2) Pink: 'So What'
2. (1) T.I: 'Whatever You Like'
3. (3) Rihanna: 'Disturbia'
4. (4) M.I.A: 'Paper Planes'
5. (-) Jay-Z & T.I. ft. Kanye West & Lil Wayne: 'Swagga Like Us'
6. (4) Chris Brown: 'Forever'
7. (8) Ne-Yo: 'Closer'
8. (12) T-Pain ft. Lil Wayne: 'Can't Believe It'
9. (53) Estelle ft. Kanye West: 'American Boy'
10. (15) Lil Wayne ft. T-Pain: 'Got Money'