The 37-year-old actress and Blanc and are overjoyed with the happy news, reported New York Post.
The couple have started to tell family and close friends they are becoming parents who have all been equally thrilled for them.
George and Blanc have been dating after over a year after first meeting at a BAFTA after-party in 2012 where they were spotted passionately kissing.
The actress previously said she was ready to have kids after finding the right man for her.
"I am going to be a mother, absolutely obvious no matter how, when, what. I really am picking the right father for my child. It's very simple. Words can't describe, sometimes, things that feel so right," she had said.