The 34-year-old singer announced the exciting news on social media on Friday, sharing a video of herself in the hospital singing "Happy Birthday" to the pair's bundle of joy.
"Happy Birthday WIN!!! Mommy & Daddy Love You! Win Harrison Wilson 7.23.2020 8lbs 1 oz," she captioned the post.
The Seattle Seahawks quarterback also took to his own Instagram account to share the family's news, posting a photo of himself, Ciara and Win.
The couple — who wed in 2016 in Chesire, England — announced they were expecting in January while vacationing in the Turks and Caicos Islands.
They're already the proud parents of a 3-year-old daughter, Sienna. Ciara also has a 6-year-old son, Future, from a previous relationship.
"I wanted to be really cautious," she told British Vogue of what it was like getting an ultrasound without Wilson. "I had a little ziplock bag of gloves for the appointment and then I had my mask. When I went from one room to the other, I switched to a new pair of gloves."
Ciara then explained that when the image of the baby came on the screen, she FaceTimed Wilson, who was waiting in the car.
"We women carry the baby, but for my husband, being in the room and listening to the heartbeat in real-time is one of his ways of connecting. For him not to be part of that was a symbol of this time that we're living through," she said.
The Grammy winner also said watching Wilson become a father figure has been a wonderful journey.
Russell Wilson and Ciara (Photo by Axelle/Bauer-Griffin/FilmMagic)
"Your son gets to see how his dad treats a woman, and your daughter gets to see how you are loved," she said.
Ciara added: "I'm a daddy's girl, and my dad's love is what saved me in situations in my life when I could have taken a left turn."
Fox News’ Jessica Napoli contributed to this report