The service will allow users to buy applications online for Windows 8-based PCs, desktops, laptops and tablets when the system launches next year.
Microsoft is offering best-selling developers a bigger share of sales than rivals' stores. Users will also be able to use some apps on a trial basis.
Experts say the move hastens the death of boxed software sold via retailers.
Traditionally most software has been purchased from High Street stores or downloaded directly from developers' websites.
However, Valve's Steam videogames service, Apple's App Store, Google's Android Market and the Blackberry App World have helped create a shift towards one-stop software stores.
Microsoft already runs a Windows Phone Marketplace where it sells third-party software.
In February 2012 it will extend that model to other devices to coincide with the beta release of the next version of its operating software.
Microsoft says the store will be global, enabling developers to sell their apps in 231 markets and in more than 100 languages.
