In her Instagram post, Joanna also shares that Chip thinks the baby is a boy.
"Chip swears he can already tell it’s a boy. Look at the little heartbeat!!" she wrote.
While Chip shared the official pregnancy announcement on Instagram Tuesday night, the ultrasound video is the first Joanna has spoken about the pregnancy.
"Gaines party of 7," Chip wrote on Tuesday beneath a photo of te couple sporting respective bumps, only one of which is from a baby. "If you’re still confused.. WE ARE PREGNANT."
The contractor and dad of four also shared some details on Tuesday night about the night that led to the conception of baby number five, saying that a "romantic" concert did the trick.
“You might recall a few months back.. the ever amazing, ever romantic @JOHNNYSWIM was in Waco. And they put on a little too romantic of a concert.. anyways, one thing led to another, & we are officially pregnant. And I could not be more EXCITED! #5 #7ThePerfectNumber," Chip wrote on Twitter.
Chip was dropping hints toward the pregnancy all night while live-tweeting Tuesday's Fixer Upper episode, including a video of him and Joanna chanting "number five."
In the episode, Joanna's sister announced that she was expecting her and her husband's sixth baby, so it's only fitting that Chip and Joanna are expanding their own family as well.
The HGTV couple is already parents to two boys and two girls, Drake, Ella Rose, Duke, and Emmie Kay.
The pregnancy could be part of the reason the couple decided to end their hit show after the ongoing fifth season, announcing in September that they wanted to spend more time as a family.
"For people, they think there's got to be a reason, like, 'Oh, something bad happened and therefore that's why they're leaving the show.' I think it's just hard for people to comprehend, no, we're just leaving because it's right instinctively for us and our family. No negative reason," Joanna told The Huffington Post.
However, as fans speculated the queen of shiplap might be expecting another child in October, she brushed off the rumors.
"There's so many [rumors], even leading up to it — I had this skincare line, so I'm leaving. It made it look like I was doing my own thing and Chip didn't even know about it. That was just a big rumor," she told ET Online at the time. "That our marriage is on the rocks...I was pregnant. Its funny when you start hearing this stuff. I was like, 'I guess people can just make stuff up.'"
This story is developing...