The tennis champion and her Reddit co-founder fiancé Alexis Ohanian welcomed their daughter on September 1.
"So we're leaving the hospital after six, seven days", the proud mom said in a video on her Instagram story.
Along with baby Alexis' first photo and name reveal, Williams also shared a montage of memorable moments from her pregnancy, including her first ultrasound, belly bump selfies and the parents-to-be assembling the nursery.
She finished off the clip with a heartwarming bio for her little girl. "But look who we got - we got a baby girl". Appearing on her mother's Instagram, Instagram stories and official YouTube page, baby girl Alexis can be seen near the end of her birth story through a series of touching videos.
In a sweet picture, Serena, 35, held the cutie - who has quite the head of hair - with the caption reading: 'Meet Alexis Olympia Ohanian Jr.
And, amazingly, she's listed as having won one Grand Slam title, seeing as her mum was pregnant during the Australian Open.