No details have been released on who Peet will play. Her episode will air sometime in January.
Peet joins the CBS comedy's plethora of guest stars this season. Chris Elliot will appear on Monday's episode and Rachel Bilson, Tim Gunn and Stacy Keibler are slated for the series' 100th episode, on Jan. 11.
This will be Peet's second project with Mother's Jason Segel, following their work together on the upcoming film Gulliver's Travels. Peet can currently be seen in the No. 1 movie in America, the world-destruction flick 2012.