After a day of rumours flying around the internet, her rep has confirmed the happy news to ELLE UK.
As you'd expect from the notoriously private actress, there is absolutely zero other information to report other than a baby is indeed on the way.
Congrats to Keira and James!
Keira and Klaxons star husband James Righton have always kept their romance well away from the limelight, although they do walk the red carpet as a couple to support each other.
They were most recently seen on 7 December, attending the Moet British Independent Film Awards together in London.
They married in a low-key, private ceremony in France back in May 2013.
It's been a pretty fantastic end to the year for Keira.
Aside from having a baby on the way, she just received a Golden Globe nomination for her role in Benedict Cumberbatch movie The Imitation Game, and it was announced she'll be making her Broadway debut next year in a production of French novel Therese Raquin.
Stars who welcomed babies in 2014:
Copyright: Rex Features WENN/Matthew Taylor/Daniel Deme/Josiah True/Matthre Taylor/Joe