The radio presenter made the announcement with a hilarious photo of her dressed in a leotard, inspired by Abigail Breslin's Superfreak dance sequence from the film Little Miss Sunshine.
"It’s gonna take more than a superfreak strip routine and a Kombi van to get me out of this one.. Jokes guys.. I’m totally pregnant and so happy my heart may burst in my chest at any moment," the 39-year-old wrote.
"Although I’m not so much little miss sunshine as little miss teary, bloated, nauseous yet ravenously hungry. Let me tell you it’s a different ball game doing this at 39 to 21.. It’s a good thing that the stretch marks are in place and ready to go!"
She later shared a follow-up post showing her growing baby bump in which she thanked her fans for their support - and revealed she was expecting a boy!
"Thank you for the bajillion messages of congrats you’ve all sent. It’s a bloody happy time for my fam and I. The other bonus- No more sucking my guts in at work.. It’s been a hectic vomit themed time but I think I’m out the other side now, oh and it’s a BOY," she said.
The wonderful news comes months after the comedian revealed she suffered a miscarriage.
The radio host took two weeks off work in May to grieve for her unborn son and spoke about the tragedy when she returned to the air waves.
“I had someone come up to me on Saturday night — I was at a dinner — to say that I was milking my miscarriage and that I needed to get over it,” she said in between tears to her co-host Harley Breen.
“I only buried my son six days ago ... I don’t know that I’ll ever get over that. I don’t think there’s a timeline on grief.”
Rusciano was 13 weeks pregnant with her son, who she and her husband Scott Barrow named “Ray Valentino” when she miscarried.
The singer and her husband already have two children, Marchella, 16, and Odette, 11.