She wrote on Instagram, "Celebrating our baby girl London with a pink Christmas."
The former "Simple Life" star initially sparked speculation that she had become a mother for the second time earlier this week when posted a picture of a pink outfit emblazoned with the word "London", which she has repeatedly said she would choose as a name if she had a little girl, alongside a pair of tiny red sunglasses and a teddy bear.
She captioned the post, "Thankful for my baby girl (sic)."
And amongst the photos from her Thanksgiving celebrations shared to her Instagram Story, Paris also posted a picture of Phoenix which was captioned, "The big brother. The socialite previously revealed she had always wanted a daughter named after the English capital.
Speaking on a "This is Paris" podcast titled "This is… I'm Pregnant??" before she had her son, she said, "One day I want to have a little girl, and I want to name her London. That's always been my dream ever since I was a little girl, because I just love London and Paris together."
"For a boy, I want to name him after a city or a country or a state as well. I have a name, but I'm not going to say it yet, I want to keep it a surprise, and I don't want anyone stealing my baby name for that one. I've said London for a long time so I can't really hide that one now," she continued.
And when she confirmed Phoenix's name, she said she had chosen a moniker that would complement London.