Lionel Richie's daughter gave birth to her own little girl ... Sofia says she gave birth on Monday, which she calls the "best day of my life."

And they've already got a name ... Eloise Samantha Grainge.

Sofia announced in January she and Elliot were expecting ... sharing with Vogue that she would give birth sometime in May or June, as she was set to have a Gemini baby. Well, she juuuust missed on that guess!

Monday was May 20, which makes baby Eloise a Taurus, officially. One day later and she would've been a Gemini.

While Sofia was excited to become a girl mom, she admitted to the publication that she and her hubby were initially convinced they were having a boy.

She shared ... "So it was a true shock. My dream in life is to have a daughter [though], and Elliot is really excited for a girl too. I think it’s so typical for boys to want boys, but he has a lot of sisters. It was really sweet. He’s very sensitive."

Sofia and Elliot tied the knot in April 2023 in a lavish ceremony in the South of France ... which is around the time the pair casually started trying to get pregnant. She first wondered if she was expecting after getting sick at a fashion show in Milan ... later confirming her pregnancy after grabbing a pregnancy test in L.A.

The rest, as they say, is history.

Since announcing her pregnancy, Sofia has happily shared her baby bump with the world ... regularly posting updates to her social media. In fact, earlier in May, Sofia confirmed on Instagram she was 9 months along, describing her journey as "bliss."