James also celebrated the newborn’s arrival by penning an adorable tribute to his own account and shared more photos of the little bundle of joy.
"On November 17, we welcomed Baby into the world. So beyond grateful for the birthing team who helped keep Jess strong through the long 28 hour birth. And most importantly grateful for the beautiful and amazing @jesshart. You’ve finally proven how much of a badass you are. The phrase “miracle of life” has never rang so true."
Many of the pair’s famous friends have sent their well-wishes, including model Poppy Delevingne who wrote: "BABY WE LOVE YOUUUU!!!!"
Nic Trufino added: "Congratulations beautiful mama! She is so lucky to have YOU as her guide 💕💕💕 light the way 👑", while Renee Bargh penned, "Ahhh she’s so gorgeous!! Can’t wait to meet her x"
Back in September, the Aussie native shared a video revealing the baby’s gender with her 258k Instagram followers.
In keeping with James’ tendency for adrenaline-fuelling activities, he asked a friend who was the only one aware of the sex to place blue or pink powder in the path of a race car.
When the engine started and a pink cloud appeared before them, the couple were overcome with emotion, cheering and hugging their nearest and dearest.
"We're so beyond excited," the brunette beauty told PEOPLE at the time. "I really thought it was going to be a boy! I don't know why. I just saw myself as a mum of boys. You just never know. I couldn't imagine it any other way now!"
Jess had announced she was expecting just a few weeks earlier when she posted a selfie holding up a positive pregnancy test.
"@jameskirkham and I are officially PREGNANT," she wrote in her caption. "We're so super duper excited about this awesome news, especially at this time and amongst the mainly bleak news out there."
"What a blessing. We're so unbelievably grateful and happy!"
Baby is James’ second child. He has a young daughter, named Wren, from a previous relationship. The athlete proposed to his love at their baby shower in October, surprising her by getting down on one knee in front of all their friends.
“What a day ! My beautiful sister threw me a baby shower on the weekend and my BEST FRIEND, baby daddy and the equally beautiful @jameskirkham came and PROPOSED to me in front of all my friends. It was so so special!” Jess wrote alongside a gallery of pics from the day. “We’re on cloud 9 over here. I was really blown away and super surprised. I had NO idea. Thank you to all of you that were there and made it so special. I love you all ❤️ (I said YES).”
The pair moved to the Hollywood Hills last February, with Jess leaving her US home base of New York after 15 years to be with her beau.
"I bought a house and I'm stoked!" she told her fans at the time.
Jess, who is the founder of natural beauty brand LUMA Beauty, previously dated billionaire Stavros Niarchos III.
