|Carey Mulligan pictured at the Met Ball 2012|
After being listed for sale two days later, the designer frock went to the highest bidder when the auction closed on Saturday with a total of 35 bidders.
The listing described the dress – the proceeds of which will go to Oxfam America - as a "piece of fashion history".
It read: "You can bid on Mulligan's custom Prada gold and silver degradé metal paillettes scaled halter neck dress. This dress has been photographed by most news outlets, from the Chicago Tribune to NY Magazine, Vogue and Style.com, and has generated significant media attention. A true piece of fashion history!
"Custom dress sized between 38-40."
This is not the first time Carey has sold one of her dresses to raise money for Oxfam.
In May 2010, she donated the Vionnet dress she wore to that year's BAFTA Awards to raise money for the charity's women's projects.
She said at the time: "I'm honored to be able to donate my Bafta dress to support Oxfam's work helping women living in extreme poverty across the world."