Fans were quick to congratulate the couple.
"Yay...he’s gorgeous! Love the name, congrats gorgeous," one wrote.
Another added, "Congratulations he is absolutely beautiful hope you and Bub are doing well."
A third echoed, "Congratulations to you both."
The Melbourne couple already share two-year-old son Aston.
24 hours prior to welcoming their new bub, Nadia posted a stunning image of burgeoning baby bump in a crop-top and leggings.
Jimmy also took to Instagram to share the news, writing: "17/10/2018 Henley Roy Bartel. Made Aston, Nadia and my world even more special.
"3.98kgs of little man that I love so much."
Jimmy added the hashtages, "Nardz You Star" and "Henley Roy."