Keri Hilson, Akon, the Scissor Sisters, actor Shiloh Fernandez and Gossip Girl hunk Penn Badgley have also signed up to model special unisex outfits as part of the Fashion Against AIDS (FAA) drive.
The clothing collection will be sold in H&M stores to raise money for charity and promote safe sex and HIV/AIDS prevention.
Blair says, "I think it's really fitting that this collection is androgynous in style since the disease affects both men and women. It's a universal thing and we are all in this together. It's a disease that can be avoided and it's especially tragic when our ignorance keeps us from safety."
Akon adds, "I've had a lot of friends who've been in the situation where their friends and family have been affected by HIV. As I travel the world, I see how much HIV affects people. It's not like we have a cure for HIV, we only have prevention. Make sure you are protected so that you don't ever have to worry about it. Ever."
The range goes onsale later this month (Apr11), with 25 per cent of proceeds being donated to the Designers Against AIDS (DAA) charity and other international HIV/AIDS prevention projects.