Gigi made the not-so-subtle announcement Thursday, updating her Instagram page bio to include "Khai's mom." Fans were quick to notice the change, and went crazy for the news.

A source close to the couple tells us Khai's name is a tribute to Gigi's grandmother -- on her dad, Mohamed's side -- who was named Khairiah. The name Khai also means "crowned" in Arabic whereas Zayn's last name "Malik" means "King" ... so baby Khai's name translates to "crowned king".

Gigi gave birth to Khai in September, and while she's shared a couple faceless photos of her new daughter, the public was left in the dark when it came to the baby's name.

It was just before Thanksgiving when Gigi shared a photo of herself holding Khai in a blanket with the caption, "A whole new kind of busy & tired ... but she’s da bestie so she got Christmas decorations early." Included was a photo of a decorated Christmas tree.