"It's a girl! Ada Elizabeth Loxley," the mother-of-three captioned a sweet shot of her cradling her latest arrival.
Alicia also shared an adorable photo of her two sons, Ned and Archie, smiling broadly whilst holding their newborn sister.
The 37-year-old previously told Nine Honey she and Kane decided to keep the gender of their third baby a surprise, noting: "If we had a girl it would be amazing."
Fans rushed to congratulate the newsreader, with one writing: "Congratulations!! Welcome to being a family of 5!!!"
Alicia shared another gorgeous photo of Ada swaddled in white linen to her Instagram story this morning.