The 27-year-old cohost of The Fabulist shared the news via Instagram, posting a picture of a baby's hat and shoes.
"Welcome Jaxon Wyatt Cutler 7lbs 11oz 5/7/14," Cavallari captioned the image.
Jaxon is the second child for the couple, who welcomed their first child, Camden, 19 months ago.
After revealing she was pregnant in October of 2013, Cavallari came under fire in March for saying she doesn't vaccinate her children during an interview with Fox Business Network. The former Laguna Beach star later defended her decision explaining: "I'm just a mom. I'm trying to make the best decision for my kid."