
The service claims more than 15 million active users.
The new owner said that it will allow Last.fm to continue to operate as an independent entity. The company plans to keep Last.fm's management team, including its three co-founders.
Last.fm operates a social networking service for music. It offers software that tracks the songs that users play and serves up recommendations based on properties such as similar genres and artists that are currently touring near the user's location.
Prior to the purchase, Last.fm raised most of its money through venture capital investors. The company expects that CBS's deep pockets will let it speed up its rate of innovation.
"This deal with CBS gives us a chance to really make Last.fm shine, and gives us more flexibility than other funding options would for doing all the crazy stuff we’re had scribbled on whiteboards for years," co-founder Richard Jones wrote on a company blog announcing the deal.
CBS expects that that Last.fm's user base will give the media giant further access to a younger, tech-savvy demographic.
"They have a great management team that understands how to build an engaged and passionate community where users learn, discover and share music globally," said CBS chief executive Leslie Moonves.
"Their demographics also play perfectly to CBS’s goal to attract younger viewers and listeners across our businesses."