EMI, whose artists include Coldplay and Depeche Mode, and Universal Music, which represents bands such as the Killers, are the first record companies to join the e-commerce programme.
Music will not be the only thing on offer. Computer games giant Electronic Arts has also signed up to push sales of its new 'Spore' game.
YouTube said the programme would be expanded over the next few months to partners across industries including music, film, TV and publishing and also outside the US.
The buttons can be added to unauthorised music videos put up by users by using YouTube's content identification and management system.
The Google-owned business hopes to develop an extra revenue stream by taking commission on sales generated by the links.
Chad Hurley, co-founder and chief executive of YouTube, said: "YouTube content partners now have the ability to promote and monetize their content in a new and exciting way and create a deeper distribution channel for their content online."
YouTube yesterday introduced a larger format video window for viewing long-format videos.