Nook for Web brings the firm's digital titles to all major PC and Mac internet browsers, meaning that users can access its library without the need for a Nook tablet.
The storefront is not accessible through the iPad's Safari browser at present, though an update amending this is scheduled for autumn. It has been speculated that support for iPhone and Android could also be added in the future.
Barnes & Noble are giving away six free e-books, including Sex and the City and Brave, to users who sign up for the service now. Free samples of each title are available online now.
Last month, a report suggested that the bookseller's Nook tablets now account for more web traffic than Amazon's rival Kindle Fire tablet.
Nook for Web is available online now.