The agreement means that customers of Apple's iTunes store will soon be able to play downloaded songs by the Rolling Stones, Norah Jones, Coldplay and other top-selling artists without the copying restrictions once imposed by their label.
EMI said almost all of its catalog, excluding music by The Beatles, is included in the deal.
Singles and albums free from copy-protection software and with a higher sound quality will be offered as a premium product, the companies announced at a London news conference.
Consumers will pay a higher price for the premium singles, but the same price for albums either with or without the copy protection software.
The announcement follows calls by Apple Chief Executive Steve Jobs earlier this year for the world's four major record companies, including EMI, to start selling songs online without copy-protection software.
The software, known as DRM, is designed to combat piracy by preventing unauthorized copying, but can make downloading music difficult for consumers.
The software used by Apple does not work with competing services or devices, meaning that consumers can only download songs from iTunes to iPod music players. The linkages between the download services and players has drawn criticism from European industry regulators, who argue that it limits buyer choice.
Jobs argued there was little benefit to record companies selling more than 90 percent of their music without DRM on compact discs, then selling the remaining percentage online with DRM.
Some analysts suggest that lifting the software restrictions could boost sales of online music, which currently account for around 10 percent of global music sales.
EMI has acted as the distributor for The Beatles since the early 1960s, but The Beatles' music holding company, Apple Corps Ltd., has so far declined to allow the Fab Four's music on any Internet music services including iTunes.
The situation was exacerbated by a long-running trademark dispute between Apple Inc. and Apple Corps. That legal feud was resolved in February when the two companies agreed on joint use of the apple logo and name, a deal many saw as paving the way for an agreement for online access to the Fab Four's songs.
Apple Corps was founded by the Fab Four in 1968 and is still owned by Paul McCartney, Ringo Starr, the widow of John Lennon and the estate of George Harrison.