New dad Connor also shared the happy news on social media, and doesn't seem the slightest bit bothered to be outnumbered by girls.
"Welcome to the world Summer Elizabeth Canning. Just like your Mum you know how to make an entrance. You surprised us 6 weeks early while your daddy was away working in Sydney!
"The world is already a better place now that you are in it. We love you," Conor wrote in his post.
The couple first announced their pregnancy last year in a sweet Instagram post, where Mary, who first starred on Matt Agnew's season of The Bachelor and went on to meet "Cleanskin" Conor on the third season of Bachelor in Paradise, shared two images of herself, Conor and her daughter, Chanel.
"I know I haven’t been active lately, so I’m happy to finally be able to share the news that me and @conorjcanning are having a baby next year," the reality star captioned her photos, proudly showing off her baby bump.
Conor also shared a post and revealed that their little family "can't wait" to meet their little one.
"We can’t wait for the newest member of our little family. @maryviturino18 and I are over the moon and Chanel is very excited to be a big sister," he penned.
Mary has been documenting her pregnancy on social media and recently revealed that the moment it all sunk in was when Conor's mum gave them gifts for the baby.
"She gave me lots of little things for the baby but look at this one, this one I was like 'Oh my gosh I didn't know that babies were so small!'," she said in a video, holding up a tiny knitted jumper.
"I knew but I forgot because Chanel's now pretty much almost my size, but look! How cute is this?"
Along with Alisha and Glenn, Mary and Conor were the two success stories that emerged from the third season of Bachelor in Paradise.
Shortly after the finale, Mary and daughter Chanel made the move to Hobart, Tasmania where Conor lives and have settled into their new home.
In a previous chat with Now To Love, the couple made it clear that they wanted to expand their family.
"I think I've always wanted a big family, so we're both keen on the idea. We'll have to see what happens down the track!" Conor said in August last year.
This story originally appeared on our sister site, WHO.