But that hasn't stopped them from congratulating him on their favourite social media site, Twitter.
Here's a look at some of the messages flooding the net.
Shah Rukh Khan: Danced with amitji & jaya aunty to all the songs i have grown up listening. Too much fun. Thanx abhishek,aishwarya & aaradhya for the warmth.
Priyanka Chopra: Happy bday @SrBachchan!! Missed the party of the decade sir but here's wishing you many many years of health and happiness..Love and regards
Sonam Kapoor: To @SrBachchan a very very happy birthday, I had the honour and privilege to work with you on black, and you are one of my main inspirations as an actor. Lots of love!
Arshad Warsi: Wishing my HERO @SrBachchan a very happy B'day n a long, healthy n happy life... Thank u for inspiring us Sir.”
Vishal Dadlani: Happy Birthday @SrBachchan Sir! There can be only ever be one 'Amitabh Bachchan'! Much love+respect, always!”
Anupam Kher: Happy Birthday @SrBachchan. May God Give you more Joy, Happiness, Peace and love. May you keep inspiring us for another 1000yrs. Jai Ho.:)”
Sophie Choudry: Happy 70th to the coolest,most stylish,talented man on the planet! @SrBachchan U put a 17yr old to shame with ur energy!Luv&Respect! #Legend”
R Madhavan: The most wonderful evening yesterday.@SrBachchan Ji Birthday Bash.Whatever the Bachchans do HAS to be classy and this was right up there.”
Neil Nitin Mukesh: I have grown up on his films. seriously for me if u say hindi films it means MR.AMITABH BACHCHAN. @SrBachchan @juniorbachchan !Loads of love “
Kunal Kohli: He's a legend. He's The Ultimate hero. He's Amitabh Bachchan.”
Shobhaa De: Eighth Wonder of the World turns 70! Happy Birthday Amitabh Bachchan...
Ramesh Srivats: And a Big Happy Birthday to Amitabh Bachchan, the Big B. The angry young man. The silly middle-aged man. The awesome old man.
Poonam Pandey: Happy Birthday Sir @SrBachchan m glad to have born in era of #Amitabhbachchan
Sammir Dattani: A very Happy Birthday to a legend & the nicest person I know out there. He gave me memories I will cherish forever! Thankyou!
Manish Malhotra: The most stylish fablaous and the best @SrBachchan happy birthday sir :-)
Farah Khan: Happy happy bday Amitji!
Shabani Azami: Happy birthday to a true gentleman