Under terms of the agreement, Viacom-owned MTV will merge its digital music store Urge with RealNetworks' Rhapsody music subscription service to form a new venture called Rhapsody America.
Rhapsody's partnership with Verizon Wireless will deliver users digital music from their PC to their mobile phones through V Cast Music, Verizon's mobile music service.
The new service will offer music from Real and MTV Network's music and pop culture brands, including MTV, which features the likes of Justin Timberlake, Avril Lavigne, Plain White T's and 50 Cent,and indie and rock channel MTV2, which features artists ranging from The Foo Fighters, to Red Hot Chili Peppers, The Pigeon Detectives and The Fratellis.
Michael Bloom, previously general manager of MTV Network's Urge, will lead Rhapsody America from offices in New York, Seattle and San Francisco.
Van Toffler, president of MTV Networks Music & Logo Group, said: "By bringing together the cultural and musical heritage of the MTV Networks family with the functionality of Rhapsody and the reach of V Cast Music, it's like we've put the best lead singer, drummer and guitarist all on the same giant stage, allowing music fans to experience the purest music play in any way they want.
"The new Rhapsody will build on the musical curation of Urge and have the marketing power of MTV, VH1 and CMT behind it."
Rhapsody America will start heavily marketing the service on air next week and at MTV's Video Music Awards in Las Vegas on September 9, but the company has declined to say when the service and products associated with the partnership would be launched.
The launch follows that of Universal Music and Sony BMG, which have already begun selling music through a new download service called Gbox. Gbox sells songs charged at the same price as market leader iTunes.
Tracks from artists such as Prince and 50 Cent can be downloaded direct from Gbox or from the online retailer Amazon, but this service is only available to US customers at present.