The Brazilian supermodel and her NFL star husband Tom Brady welcomed their little girl, Vivian Brady, into the world on 06.12.12, according to the Boston Globe newspaper.
No further details about the birth are yet to be released.
The couple already have a two-year-old son, Benjamin, together, while Tom - who plays football for the New England Patriots, who are based in the Greater Boston area - has a five-year-old son, John, with ex-girlfriend Bridget Moynahan.
It was recently reported Gisele wanted to have a little girl but refused to find out the sex of her baby during her pregnancy.
A source said: "She`s hoping it`s a girl - she loves little girls. But she wants to be surprised like when she had her first baby Ben."
The 32-year-old beauty has previously spoken about her love of being a mother and said she wanted lots of children.
She said: "I want to have a big family. I love kids."
Tom has also said he is keen to have lots of children, but balance it with having a successful career.
He said: "I have to do something [after football]. The only thing I ever wanted to be was a professional football player. It`s hard because I want to have four kids and I want to be a really good dad, too."