Tanner, 33, revealed Saturday on his Instagram Stories Baby No. 3 arrived at 5:33AM.
"Mama and Baby Boy doing great," Tanner shared.
And Jade posted a photo of herself with the newborn on her own Instagram account, writing, "He's here and he's perfect."
While neither Jade or Tanner disclosed the baby boy's name, Jade teased how she will "share all the magic" and her "birth story" with fans at a later date.
"Right now we are soaking in all these beautiful, new moments. Thank you for all the love and support and for holding space for our little family in your hearts. I'm one grateful mama," Jade wrote on Instagram.
Jade and Tanner's little bundle of joy joins the couple's 15-month-old son Brooks Easton and three-year-old daughter Emerson "Emmy" Avery.
After Jade delivered her son, Tanner uploaded an image of himself holding the baby above Jade's birthing pool as she sat in the water and smiled at the camera. When this photo was taken, the infant's umbilical cord was still attached.
"Officially outnumbered! [three baby emojis]," Tanner captioned the post along with three baby emojis.
"We are SO excited and thankful to be welcoming a healthy baby boy into our family!" Jade told E! News at the time.
"[Our daughter], Emmy, Tanner and I all were all putting our bets on a girl, but this is truly such a fun and happy surprise! It may take a while for Emmy to call the baby brother though. She is still referring to him as sister."
"I'm so grateful," she added, "and I'm so happy we decided to find out before the baby is born. It gives me something to look forward to and I feel even more bonded to him now."