It follows a similar agreement between the advertising site and Mini's parent, BMW, in December 2007.
The move comes four years after BMW and Mini launched an ongoing initiative with Autotrader.co.uk, which highlights all vehicles in the brands' approved programmes and the benefits that come with choosing a manufacturer approved used car.
Suzie Hewitt, dealer marketing manager for Mini, said: "As more of our dealerships prepare to take advantage of this new relationship, we expect to see the volume of cars loaded onto exchangeandmart.co.uk rise sharply with a potential 4,000 to be added.
"The site offers our dealers a highly flexible package that is easy to use, making uploading of stock fast and efficient’."
Vehicles in the BMW Used Approved and Mini Cherished programmes are already being uploaded.