The multi award-winning actress - who was married to CNN founder Ted Turner from 1991 to 2001 - will play media mogul Leona Lansing in the Social Network and Moneyball writer's new project, TV Line reports.
Provisionally titled Newsroom, Sorkin's drama stars Jeff Daniels as cable news network anchor Will McCallister and Emily Mortimer as his executive producer.
Slumdog Millionaire's Dev Patel and Magic Mike actress Olivia Munn also feature in the ensemble cast.
Mortimer recently described her character Mackenzie McHale as "charismatic... crazy [and] demented", quipping that Newsroom will also feature Sorkin's trademark "cool chit-chat [while] walking down endless corridors".
The programme was taken to series by HBO earlier this year under the original title More As This Story Develops.
Newsroom is expected to premiere in 2012.