The New Girl star, 34, is expecting her first child with boyfriend Jacob Pechenik, 42. "Jacob and I are over the moon. We are so excited to meet our little one," Deschanel said.
Deschanel has been dating Pechenik, a producer, since mid-2014. She was previously married to Ben Gibbard from 2009-2012. It's unclear if her pregnancy will be written into New Girl.
The actress' sister, Bones star Emily Deschanel, is also pregnant and expecting her second child with her husband, It's Always Sunny in Philadelphia's David Hornsby.