In the social media post, the 'Manmarziyaan' star also advised the "coolest kid in the world" to remain the "mamu's pet" that she has always been.
"To the coolest kid in the world. Happy 21st birthday my Navya," Abhishek wrote on Instagram, along with a picture of the birthday girl.
Junior Bachchan went on to add, "You are now "officially" a little lady, and a very generous, loving and caring one at that too."
"From a baby who used to fit in the palm of my hand to becoming one of my dearest friends, you've always been mamu's pet. Never change! Love you!," her uncle, Abhishek wrote in the post.
The entire Bachchan clan dotes on Navya, daughter of Shweta Bachchan Nanda and Nikhil Nanda. She is often spotted hanging out with grandpa and megastar Abhishek Bachchan and also frequently appears on his social media handles.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)