Re-sale website Vestiairecollective.com launched the initiative on Thursday (21Nov13) to mark the start of the festive season, with a special section on their website dedicated to the sale of items previously owned and loved by the British celebrities.
Prices start from $150 (£100) and items up for sale include Weisz's hot pink Joseph wool dress, a frock owned by model Daisy Lowe and a crystal-embellished dress worn by Jessie J on tour.
Other well-dressed ladies who have donated to the second annual sale include MTV presenter Laura Whitmore, model Jade Parfitt and designer Jasmine Guinness.
Profits from the sales will be handed to a range of charities selected by the donors including Barnardo's, Doctors Without Borders and the National Society for the Prevention of Cruelty to Children (Nspcc).
Vestiaire Collective's U.K. Managing Director Fanny Moizant, says, "We are thrilled that so many leading lights in the fashion world have come out to support our annual charity initiative - this year we expect to raise thousands for charities... We have a treasure trove of fashion gems on the site, and we expect many of these pieces to become valuable collectors' items so we advise fashion hunters to come early."