In the deal struck late Tuesday night, they agreed that five of Viacom's "big six" networks will remain on Spectrum's "select tier," which is their base subscription package. Spectrum reaches more than 16 million subscribers nationwide.
The move is seen as a positive for Viacom. There had been concern that Charter, which last year acquired Time Warner Cable, would not keep all six of the networks, which include MTV, Nickelodeon and Comedy Central.
Tuesday's deal includes those three channels, BET and Paramount as well as VH1, CMT and TV Land. A ninth channel, Nick Jr., is on another subscription tier.
Viacom shares are down 28 percent this year. They were down more than 2 percent in morning trading on Wednesday.