The 30-year-old star shared the snaps of baby Otis dressed in a tiny grey hoodie (complete with ears!) while being cuddled by his mummy alongside the caption: "Rock and roll, baby."
All together now... Awwwww!
While this isn't the first time we've seen a snap of the wee baby, it is the first time we've seen his gorgeous face.
Olivia recently admitted her son - who was born in April - has given her and her fiancé Jason Sudeikis a new prospective on life.
But she also confessed she finds it a struggle trying to balance her new role as a parent with her demanding career.
"The amazing thing about becoming a mother is it snaps everything into focus and really makes you understand what's important," she told People magazine.
"It's [parenthood is] tricky! It's tricky for every mother, and I salute working mothers everywhere. We are warriors. Suddenly these press lines are less stressful!"
The post follows a rather ridiculous claim from GQ film critic Tom Carson who claimed that Olivia's "tush" means she can't also convincingly play an intelligent woman in her latest movie.
In a review of the filmed Third Person, Carson said: "She's supposed to be a writer, but your belief in that won't outlast Wilde scampering naked through hotel corridors once [Liam] Neeson playfully locks her out of his room. With that tush, who'd need to be literate? Who'd want to?"
But Olivia, being the total kickass Hollywood heroine she is, responded in the most perfect way possible. Click here to find out what she said.
LOVE OLIVIA? See more from her in the gallery below.
MORE! Of course Liv looked amazing just days after giving birth..