The trio - along with the likes of David Walliams, Duffy, Rupert Grint and Leighton Meester - have generously given away one of their prized possessions for Give Up Clothes For Good, a campaign to help raise valuable funds for life-saving research into childhood cancers.
The clothes will be available on internet auction site eBay, who are working with the UK's biggest charity Cancer Research UK and brands-for-less retailers TK Maxx and HomeSense on the campaign.
Sharon said: "I've donated my favourite Burberry coat for the Give Up Clothes for Good campaign. I know that donating it will help to raise money for an amazing cause - beating childhood cancer."
Nicky - who has given the dress worn at her New York fashion week debut - added: "I love this dress. I wore it on the runway of my show at Bryant Park during New York Fashion Week 2009, it was a hit! Being part of the Give Up Clothes for Good campaign is a fun and simple way to support an amazing cause."
Other items include David's Tom Ford suit, Tyra's Balenciaga dress and a dress worn by Duffy at Chicago's Lollapalooza Festival.
The auction - www.txmaxx.com/ebay - went live today (25.03.10) and will close next Thursday (01.04.10) at 3pm.