The advertising-funded service, powered by Rhythm NewMedia, allows all 3 customers in the UK to access videos through 3's music homepage.
Customers can view videos without receiving data charges, and the service will be supported with video advertising.
Rhythm NewMedia will handle sales and delivery of targeted video advertising before the music videos play, based on demographic data.
Adverts will be no longer than 20 seconds, and will be targeted based on age and gender.
The new Sony BMG collection will bolster 3's existing free mobile video service, and the network claims that links to purchase products via the music video service will complement the 3MusicStore.
3 first introduced advertising-funded video last March, and announced that more than one million customers had signed up to its service in the first six months. Brands that have already signed up to run pre- or post-roll advertising on the service include Cisco, Intel, Lynx, Ministry of Sound and Paramount Pictures.