The singer-and-actress and her husband Mike Comrie welcomed son Luca Cruz Comrie into the world on Tuesday (20.03.12) and the couple are thrilled with the new addition to their family.
Writing on her twitter page, Hilary - who married former ice hockey player Mike in 2010 - said: "Welcome to the World Luca Cruz Comrie! Tuesday evening, we became proud parents of a healthy 7 pound 6 ounce beautiful boy.
"We are overjoyed and feel like the luckiest parents in the world."
Hilary, 24, was thrilled when she found out she was pregnant and admitted she couldn`t wait to meet her son.
She said: "People keep saying to me, `Sleep right now. Get your sleep!` I keep saying, `I just want the baby here! I want to play and I`m ready to see what he looks like.` "
Before the birth, Hilary was thrown a baby shower by her close friends and family and admitted she had an "amazing" time.
She tweeted afterwards: "What an amazing day my mommy and @HaylieK threw it down!best baby shower!This baby is spoiled already! And this mama is wiped out!!
"So grateful for all my friends and family that love and support me through all these huge milestones in my life! Such special memories today! (sic)"
The shower - which was hosted by Hilary`s mother Susan and sister Haylie - took place at the former `Lizzy McGuire` star`s Los Angeles home and was "small and intimate", with around 40-50 guests.