The company made a firm commitment to buy the channel which has been in administration after Murdoch, James Packer and Gordon refused to guarantee support for a loan of $200 million to keep the business going.
CBS' entry into the Australian market means that one of the major TV networks will now be in foreign hands. But Channel Ten has been owned by Canadian interests before this.
The Australian billionaires appear to have been waiting for media ownership laws to pass parliament before making a bid for the network. But with the laws still held up as senators haggle over them, the prize has gone to the Americans.
Rupert Murdoch's empire will face a hit on two fronts: first, the Fox group was providing a number of programmes to Channel 10, an arrangement which will presumably cease.
Additionally, CBS is said to have plans to launch a digital subscription video-on-demand service which will go up against Foxtel which is half owned by Murdoch.
Shadow communications minister Michelle Rowland described the deal as being "good news for the provision of news and current affairs and the public interest in maintaining a diversity of voices in the Australian media landscape".
"The CBS chairman and chief executive also expressed his confidence in growing Network Ten by applying the programming expertise of CBS," she said in a statement.
Rowland said Ten and CBS had a longstanding relationship and, "while it is encouraging that CBS have stated publicly that they look forward to expanding on Network Ten’s 'great legacy of Australian news, drama, reality and sports programming', it highlights that caution must be exercised in reforming safeguards for Australian and children’s content".