The new offering will be compatible with most personal music players including PCs, Macs, iPods, Zunes and Zens.
EMI Music's digital catalogue is the latest addition to the store and every song and album in the Amazon.com digital music store will be available exclusively in the MP3 format without digital rights management (DRM) software.
Jeff Bezos, Amazon.com founder and chief executive, said: "Our MP3-only strategy means all the music that customers buy on Amazon is always DRM-free and plays on any device.
We're excited to have EMI joining us in this effort and look forward to offering our customers MP3s from amazing artists like Coldplay, Norah Jones and Joss Stone."
EMI recently announced it had come to an agreement with Apple to sell its back catalogue and current tracks through its iTunes store without DRM.
Eric Nicoli, EMI chief executive, said: "Amazon.com is known around the world for the unique experience it offers music customers through features such as customer reviews and personalised recommendations.
"We think having a trusted destination like Amazon.com offering a high-quality digital music product that will play across a number of devices gives consumers more options and will be a significant boost for the overall digital music market."
Other major record labels are considering moving to DRM-free MP3s but are still testing the logistics of this idea. Many are worried that to drop the copyright protection would leave them open to piracy.
Presently, Apple commands 80% of the online music download market despite rival offerings from Microsoft, Yahoo, MySpace and a myriad of independent download sites.