The new service, hosted on the Sainsbury's Entertainment website, provides customers with access to over 2.3 million downloads - including tracks and albums.
The catalogue of music contains tracks starting at 89p, chart albums from £6.99 and 'Deal of the Week' albums for £4.99 - with a limited-time user incentive of the first individual track download from the service being free (offer ends May 6).
These downloads also gain Nectar points -Sainsbury's loyalty points collection scheme.
Sainsbury's is also guaranteeing the lowest prices its on pre-order items as part of a competative pricing ethos. When an MP3 is purchased and the price drops ahead of, or on the release date, Sainsbury's will refund the difference.
The website has been launched with the aim of being simple and user-friendly 'to help customers get what they need quickly, with clear instructions from how to download and build a playlist to a unique preview function, which allows consumers to listen to music ahead of purchasing it.'
Mark Bennett, head of Entertainment (Online) said: "This launch of our new MP3 music service enables our customers across the UK to get digital music at great value. This is the first step in our expansion to offer digital entertainment alongside our existing range of CDs, Games, Film and books catalogue."
Peter Selby, music manager added: "'Downloading Made Easy' is central to our music offering and we have ensured that the process is as simple as possible for all our customers, who can be safe in the knowledge that all their favourite music will be will be available at the touch of a button."