The 27-year-old Jersey Shore star told the magazine she was "super excited and emotional" to find out the baby's gender.
"I pictured a boy this whole time, so when I saw 'girl' on the paperwork, I was like, 'No way!' But deep down I think I knew," she says. "[Snooki's son] Lorenzo is gonna have a BFF, and I couldn't be happier!"
"She will be my best friend and daddy's little girl," the mom-to-be added. "I can't wait for everything from her first steps to her first dance class."
Farley said that her daughter's teenage future is what scared her the most.
"I was a teenage girl once, and, boy, do I know how sneaky we can be!" she said. "Karma is gonna kick me in the butt with her!"
However, her fiancé Roger Matthews is looking at the baby's eventual teen years from a different perspective.
"He was just saying today what kind of car she'll get for her sweet 16 if she gets good grades," she told the magazine, adding the father-to be "can't stop talking" about the news.
The baby, due in July, will be Farley's first with Matthews.