The US X Factor host and hubby Lamar Odom have set up a store on the website to flog their unwanted belongings.
And reality star Khloe recently added a whole heap of her clothes to the site, including some pre-owned sports bras and jogging bottoms.
Khloe tweeted a link to the eBay page yesterday, and added: "New year, new wardrobe!"
Among the items up for sale are an Under Armour Heat Gear White Sport Bra Size M, a Nike Fit Dry Purple Sports Bra Size S and a pair of Kardashian Kollection Grey Drawstring Tie Sweatpants Size M.
The site reveals that all sold "auction items benefit Cathy's Kids".
The charity, set up by LA Lakers star Lamar, helps under-privileged kids and supports efforts to find a cure to cancer.
Lamar lost his mum to the disease when he was just 12.