Bachchan, the elder statesman of Bollywood, hit the red carpet with his family on Wednesday night for celebrations in the entertainment capital Mumbai, where he was joined by a star-studded list of 800 guests.
Outside his residence in the city, fans gathered on Thursday to present flowers and chant "Long Live Amitabh!" but the birthday boy struck a modest note.
"Birthdays are special for all... mine is no different... but (it) would never be the same without your love and affection," he said to his more than 3.5 million Twitter followers.
Among the film, business and political bigwigs at the party was fellow acting superstar Shah Rukh Khan, who tweeted that he had "too much fun" dancing with Bachchan and his wife Jaya, who organised the bash.
On Thursday Bachchan was due to open a mobile diabetes van at a Mumbai hospital.
Known universally as "The Big B", Bachchan made his name as the "angry young man" of Hindi cinema. He starred in more than 150 films including the 1970s hits "Sholay" (Embers), "Deewaar" (The Wall) and "Don".
Still acting in several films a year, he was voted "actor of the millennium" in a BBC online poll in 1999 and became the first Indian actor to gain a lookalike at London's Madame Tussauds waxworks museum.
"I just feel that so long as I have life and I have breath inside me, I should continue to work," he told the DNA newspaper in an interview marking his birthday.
Bachchan's legions of admirers monitor his health closely: he was discharged from a Mumbai hospital late in February after undergoing surgery twice for an abdominal problem.
He also nearly died following an accident on the set of the 1982 film "Coolie" where he ruptured his spleen during a fight scene.
Fans at the time prayed for his recovery, holding vigils outside his hospital and making offerings at temples and mosques.
The veteran actor is a ubiquitous figure in Indian life, hosting the local version of quiz show "Who Wants To Be A Millionaire?", supporting charity causes such as protecting tigers, and featuring in countless advertisements.
He is set to make his Hollywood debut with a fleeting appearance in the new adaptation of F Scott Fitzgerald's 1925 novel "The Great Gatsby", starring Leonardo DiCaprio and due for release next year.
COMMENTS (9)
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ
@1984 Only Talibani leaders cross 70 in Pakistan, if they protect themselves from Drones..
@zabdesk: Considering the fact that rejecting polio vaccines,terrorism,target killing,poverty etc...
Soon,Pakistan will celebrate when someone actually crosses 70 yrs....
zabdesk
Everyone is NOT Amitabh Bachan.
Who cares.
@zabdesk True brather he is not a muslim , ET should not publish such news
Whether it is a news? Everyone who has born 70 years ago is celebrating it.
How times have moved on. In Pakistan any bollywood star who was not a muslim was a kafir and ignored. All they could remember was Mohd Rafi, Dilip Kumar, Nargis, ShahRukh etc. Hats off to the new generation of Pakistanis and happy birthday Mr Bachchan. You sure are a legend - just like Dilip Kumar.
khans + Kapoors + kumars < Amitabh Bachan