The 42-year-old Jagged Little Pill hitmaker made the exciting announcement on Instagram on Friday (08Jul16), posting a close-up photo of herself nursing her newborn daughter.
She added the caption: "she's here! onyx solace morissette-treadway June 23 2016 #beyondblessed".
Little Onyx is the second child for Alanis and her rapper husband Mario 'Souleye' Treadway. The couple is already parents to five-year-old son Ever Imre.
The Ironic star managed to keep the 23 June (16) birth of her daughter a secret until now, partly because reports suggested the tot wasn't due to be delivered until the end of the summer (16).
Just under a week after she went through labour, the clever musician distracted fans, the public at large and the gossips from the baby's delivery by posting a gorgeous underwater nude shot of herself on social media on 28 June (16).
The otherworldly aquatic picture featured pregnant Alanis peacefully floating in a pool with her baby bump on full display.
The accompanying photo caption contained a quote generated by her son Ever, reading: "you have to be extra gentle around ladies because they are the most helpful people in the world 'cause they make persons."
Morissette confirmed she and her husband were expecting their second child in February (16) in a sweet video that ended with Ever gazing at the ultrasound photos of little Onyx.
"The story of my nuclear family in moving pictures, brings us up to this sweet moment,” the video’s caption read.