The new parents, whose son was born on December 1, have named him Azad Rao Khan.
Khan wrote: "Hey guys, most excited to share with y'all that we have finally chosen a name for our baby boy... Azad. Azad Rao Khan. I left the final choice to Kiran, and she has named him after my great grand uncle Maulana Azad, the great freedom fighter, whom the family is most proud of.
"Azad means free or liberated. We want to thank everyone for their warm wishes and blessings, and needless to say we are absolutely overjoyed and feel most blessed. Much love. a."
The baby was born through IVF to a surrogate mother at a private clinic in Mumbai.
The 46-year-old actor announced the birth with a letter sent to media organisations asking them to respect his family's privacy.
While there has been no reaction from the film fraternity to the birth, the actor's Facebook page has been inundated with congratulatory messages from over 4,000 fans.