In the picture, Riteish, 37, is seen holding his son in his arms.
"It's a special day coz its my Aai's Birthday & on this special day I would like to share something special. #RAHYL #HappyBirthdayAai," Riteish posted alongside the picture.
Riteish and his wife Genelia Deshmukh welcomed Rahyl in June.
They are also parents to son Riaan, who was born in 2014.