The 2012 actress will appear on the CBS comedy in January. She will play a co-worker of Jason Segel's Marshall, reports Zap2It.
Peet will next be seen in indie filmmaker Nicole Holofcener's Please Give. She is currently working on the Gulliver's Travels movie starring Segel.
How I Met Your Mother, with Jason Radnor, Cobie Smulders and Neil Patrick Harris, airs Mondays on CBS.