In October 2015, for its debut, Comet had affiliation agreements with television stations covering 60% of the United States (or 150,891,489 households with at least one television set). By July 2016, the network had grown to 72 markets covering 72% of U.S. TV households.

Sinclair Broadcast Group initially planned to launch Comet on select television stations owned by the company (including those operated through outsourcing agreements with partner companies Deerfield Media and Cunningham Broadcasting). The network also intended to seek carriage on the digital subchannels of television stations owned by other broadcasting companies. Titan Broadcast Management and Tribune Broadcasting were the first outside of Sinclair operated stations to affiliate some of their stations with Comet.

Due to its co-ownership by Sinclair, some of the group's stations (as well as others not run by Sinclair, Deerfield or Cunningham that are affiliated with the syndication service) may elect to pre-empt certain afternoon and/or evening programs within the national Comet schedule to carry telecasts from the Sinclair-owned American Sports Network. This capacity is currently utilized by Sinclair for many of its The CW and MyNetworkTV and other affiliated subchannels as an alternate outlet to air events not being carried by the affiliate's main channel.

A full list of affiliates can be found via Wikipedia.