"Ever since the earthquake, I've been trying to do my part to help the people of Haiti – and I wanted to do more," Cyrus tells PEOPLE.
Starting Feb. 8, fans can go to Ebay.com/Miley to bid on the Herve Leger dress the singer wore to the Jan. 31 Grammy Awards as well as two tickets to the Hollywood premiere of her upcoming film, The Last Song.
Cyrus recruited a bevy of famous friends to chip in too: Nicole Richie donated jewelry from her House of Harlow line and Britney Spears offered up the custom silver Versace minidress she wore to 2008's MTV Video Music Awards.
"Everyone has been so generous," says Cyrus, 17. "My mom and I started calling and texting all of our friends to see if they’d like to be a part of the auction. Demi [Lovato] was one of the first to respond. Hugh Jackman was also excited to donate something."
As for Richie's contribution, Cyrus says she relied on some technology to reach out to her. "I texted Nicole and right away she sent over some amazing jewelry and Joel [Madden] sent some of his clothes."
With all proceeds going to the American Red Cross to support emergency relief efforts in Haiti, "I want to get people involved and show that even the little things you can do can make a difference," Cyrus says.
Giving back has also become a family affair.
Miley's big sister, Brandi, will perform with her band Frank & Derol at Harmonies for Haiti, a charity concert organized by Disney Channel star Chelsea Staub, on Feb. 11 at the House of Blues in West Hollywood.