Robin looked fabulous strutting down the runway bald, in a brick-red sequin dress from Isaac's Fall '08 collection.
"This is who I am," Robin said with a smile about her decision to ditch the wig.
"I'm on the air without the wig and without underwear as well…totally commando," Robin revealed with a laugh to Chris Cuomo and Diane Sawyer who were watching with pride and cheering her on from the studio.
"It's all about confidence," Elle Editor and Project Runway host Nina Garcia explained to Robin after the show. "You have it. You look amazing and you showed us."
Robin followed "America's Next Top Model" Danielle Evans down the catwalk, careful not to step on her dress. She said her biggest fear was not falling, but causing a 16-model pile up behind her.
Isaac's entire collection and the full runway show can be seen on his Web site by clicking here: IsaacMizrahiNY.com.
Why and how she did it
"The story of my dare began back in July of last year when I was first diagnosed with breast cancer, knowing only that a battle lay ahead," Robin explained.
The last thing Robin says she felt was beautiful. "So when GMA dared me to be a model, it was the perfect opportunity for me to really push outside my comfort zone," Robin said.
To transform herself into a supermodel, Robin sought help from the best.
Tyra Banks showed Robin how to walk the runway. Click here to get more of Tyra's catwalk tips.
Next Robin went to see designer extraordinaire Isaac Mizrahi, who agreed to give her a chance and helped her find the stunning red sequined gown she wore.
The last step before the show was the obligatory photo shoot. Supermodel Nikki Taylor showed Robin how it's done for a special layout in Redbook magazine.