The Big 12 have a pair of contracts with ESPN and FOX Sports. Both contracts expire after the 2024-25 athletic year with a six year extension agreed to but not announced by the conference through the 2030-31 athletic year.
For the 2023 and 2024 football seasons, the ESPN deal allows for 32 games per year and games can air on ABC, ESPN, ESPN2, ESPNU, ESPN+ and Longhorn Network (see note below re: LHN), though I assume that there will be an incremental increase for ESPN due to the increase in inventory with 14 members. FOX's deal is for up to 40 games per year to place games on FOX broadcast network and various FOX Sports pay TV platforms, though this may also be adjusted for the 2023 and 2024 seasons. A minimum of six of FSMG's games must appear on FOX with another six on FS1. Overall, a minimum of 25 games must air on ABC, ESPN, FOX and FS1. Starting in 2017, the conference reactivated their championship game. ESPN has the rights to the conference championship game to air on ABC or ESPN.
Big 12 selection order for each week will be determined via a draft of weeks before the season. In even numbered years, FOX will retain the top choice of weeks and in odd numbered years, ESPN wiil have it.
Individual institutions retain the rights to at least one game not aired by ESPN or FOX Sports, allowing those institutions to explore other avenues to televising those games. All schools except for Texas will air their institutionally held games on ESPN+. Starting with the 2025 season, all institutional rights will be removed and part of the national TV packages.
Starting with the 2025 season, ESPN will be the primary rightsholder. They will have priority for choosing the top four selections for the entire season and then roughly alternate with FOX Sports through the top 20 selections.
Regarding Longhorn Network, one Texas game per year airing on the network counts as an institutional game, like all other Big 12 schools. Any subsequent Texas games airing on Longhorn Network will count towards the ESPN contract.
Source: Big 12, ESPN (championship game and member retained content), Sports Business Journal (contract extension)