The network announced Monday that Roberts was joining the network as a senior national correspondent.
Roberts was most recently a host of CNN's "American Morning," but he was bumped from that job when the network announced a reorganization last month. He had been discussing a transfer to Atlanta, home base for his fiancee, CNN anchor Kyra Phillips.
Roberts spent 14 years with CBS, working as a White House correspondent and anchor of the weekend evening news. He joined CNN in 2006.
Fox executive Michael Clemente says Roberts' "reputation as a skilled journalist with years of notable experience in the field will be a valuable addition to our news programming.