Saif and Kareena were blessed with a son, whom they have named Taimur Ali Khan Pataudi.
"Delighted to welcome Taimur Ali Khan Pataudi into the world. Both mother and son are healthy and doing well. Father is doing extremely well," Soha tweeted.
Veteran actor and Kareena's father Randhir Kapoor says the family is ecstatic about the new addition. He has also thanked friends and fans for their blessings.
Randhir told IANS: "The entire family is overwhelmed and is welcoming the new member in our family. Both the mother and son are doing fine. Thanks for all the blessings."
Taimur is Kareena's first child with Saif, who already has two children -- daughter Sara and son Ibrahim -- from his previous marriage to Amrita Singh.
The couple's star friends sent in congratulatory messages on Twitter. Here's what they have said:
Karan Johar: My Bebo had a baby boy! I am so so happy! Taimur Ali Khan.
Sonam Kapoor: Congratulations my darling Bebo and Saif! Taimur Ali Khan Pataudi is going to be the apple of everyone's eye... Mini nawab.
Tusshar Kapoor: Even more glorious life with God's blessing in hand! Cheers to Saif and her both and peace and everlasting joy to the little prince.
Sophie Choudry: Congrats beautiful Bebo and Saif on the birth of your baby boy! Such amazing news! God bless! Taimur Ali Khan. Baby boy Kareena Kapoor Khan.
Monica Bedi: Congratulations to Kareena Kapoor and Saif Ali Khan for becoming super parents! Enjoy this new chapter! Taimur Ali Khan.