The 27 year-old 'The Hills' star shared the news via Instagram in which she posted a photo of a pair of small slippers and a hat of the baby boy, reported Contactmusic.
"Welcome Jaxon Wyatt Cutler - 5/7/14," read the caption of the photo.
The couple, who married in June 2013, are already parents to a 20-month-old son, Camden.
"I'm lucky," Cavallari said in an interview while talking about her pregnancy.
Cavallari earlier also said that having another boy would give Camden "a little buddy and then I'd be the woman of the house.