The actress and her fiance, sports agent David Gardner, welcomed their second child together over the weekend. She posted a photo of Gardner cradling little Lula Rose in his arms on Instagram on Sunday and added the caption: "Hello!!!!! Our beautiful baby girl is here!!!! Lula Rose Gardner We are soooooo happy. heart exploding with love!!!!!"
Liv and David are also also proud parents to one-year-old son Sailor Gene, while the 38-year-old star has an 11-year-old son, Milo, from her marriage to British rocker Royston Langdon.
Gardner also has an eight-year-old son from his marriage to actress and socialite Davinia Taylor.
Tyler announced she was pregnant in January, tweeting: "Oh my goodness it seems the stork is visiting us again... Our family is growing!!! So grateful. @davidgardner I love you."
The actress has also been posting her pregnancy progress on Instagram, and just last week, she captioned one shot: "Ohhhh my goodness look at that bump so pointy and giant!! I can't wait to meet the beautiful little human living in there..."
It appears the newborn will be Tyler's last baby - she recently said, "I have been pregnant for two years straight. It feels like for ever... I think we will be done after this."
Read more: Liv Tyler’s nutty third pregnancy
And she previously told Britain's Metro newspaper, "I didn't know I was going to have two babies in two years. It's the nuttiest thing that could have ever happened to me."
But motherhood suits the Armageddon star - she told the outlet it brings her "a sense of calm".
"Having a baby and growing a baby is probably the most challenging thing that you will ever do," she added. "Then when I go to work I feel much more free in away. It's definitely changed me."