The US catwalk star, 28, told her nine million Instagram followers her little boy was named Levi Joseph.
Kloss shared a sweet picture to social media showing her holding the baby’s tiny hand. She wore a gold ring spelling out the word “Mama”.
In the caption, she confirmed Levi was born on March 11th. He is her first child with businessman husband Joshua Kushner.
Kloss’ friends from the fashion industry shared well-wishes in the comments.
Model Lily Aldridge said: “Cutieeeeee I can’t wait to meet him.”
America’s Next Top Model presenter Tyra Banks said: “Hey mama.”
And Brazilian model Adriana Lima wrote: “Congratulations mama.”
Kloss married Kushner, 35, in a small ceremony in New York in October 2018.
He is the brother of former president Donald Trump’s son-in-law and former senior adviser Jared Kushner.