The actress—who is also mom to two daughters, Naleigh, 8, and Adelaide, 4—debuted the photos via this week's issue of People magazine. In the cover story, Heigl shares details of the experiencing her first pregnancy, which came as a surprise to her and husband Josh Kelley.
"I'll be totally honest, my first reaction was 'Oh s—,'" the 38-year-old explains in the interview. "But now we have a new normal, and I have to give myself a break in order to get used to it."
The too-cute cover shot features the Knocked Up star smiling as she cradles the newborn, who is dressed in a blue-and-white striped onesie.
While the timing might not have been ideal as the star had just started work on her new CBS series Doubt, Heigl revealed that the news was a blessing as she had been thinking about expanding her family.
"I knew I wanted to have more children," the actress admitted. "I just didn't know how we were going to go about that."
@joshbkelley and I are beyond thrilled to finally share the arrival of our little man Joshua Bishop Kelley Jr born December 20th, weighing in at 7 pounds 15 ounces. We are all happy, healthy and beyond grateful! For more pics and the exclusive story check out @people magazine (out Friday) who I must profusely thank for helping us to announce our happy news in a beautiful, honest and loving way! I also want to give a big hearty loving shoutout to my bestie @cheyenneellis for the gorgeous photos including this one! And one more GIANT thank you to all of you for your wonderful words of support, love and all those beautiful well wishes! As always I am incredibly grateful to have such wonderful fans! ❤️❤️❤️❤️❤️❤️
In the interview, the Grey's Anatomy alum also opened up about the future and her "investment in adoption," which was inspired by her older sister Meg, who was adopted from South Korea. Heigl and Kelley adopted their older daughters in 2009 and 2012.
"I'd get pregnant again, and I still am very inspired by adoption. I also have been thinking a lot about fostering. It's all up in the air," she revealed, adding. "And I'm okay with that."
Since being brought home, little Joshua seems to have settled in and be getting plenty of attention from his big sisters.
"This little boy is going to have all these girls fawning over him!" the proud mom said. Check out this week's issue of People, out Friday, for more from Heigl and additional photos of the newborn.