The couple used their 19-year-old daughter, Luna, and Chrissy's social media to tell the world.
On Nov. 21, Chrissy posted an Instagram video of Luna. As the Sports Illustrated model refers to her stomach she says, "Luna, what's in here?" The little one says, "baby."
Chrissy shared the video, captioning it, "it's john's!"
There has been speculation for several weeks that Chrissy may be expecting. Many felt that they saw a hint of baby bump while she attended a Forevermark Diamonds event in New York City on Nov. 7. Further photos show her wearing flowing dresses and using large handbags to cover her belly.
The couple has spoken about their desire to have more children. In June, the model said she would be open to having children naturally or by other means.
"I would definitely adopt or have foster children," she told Marie Claire. "But I loved being pregnant. Maybe I should be scared [of having postpartum depression again], but I don't know. It couldn't be any worse than it was - could it?"
Last year, Chrissy explained on her talk show, "FABLife," that she and John were having trouble conceiving. The star admitted to undergoing IVF, and further confessed how difficult it was to field baby questions over the last few years.
In February, she and John endured criticism after revealing they'd selected the gender of their child.
"I've made this decision," she told People magazine. "Not only am I having a girl, but I picked the girl from her little embryo. I picked her and was like, 'Let's put in the girl.'"
In January, she said their next child would be a boy.
"Since this is coming up again, I said our next baby would be a boy because that is the embryo we have left. A boy. So. Yeah.," she said. She then added at the time, "And no, I am not pregnant."