The 73-year-old actor, who is admired for movies like Sholay, Deewar and Piku, shared the news on his Twitter on Sunday:
T 2263 - 21 MILLION !! followers .. thank you all for this .. 25 MILLION here we come !!! pic.twitter.com/btx87lqQP5— Amitabh Bachchan (@SrBachchan) May 21, 2016
On his blog , he posted: "It is 21 million on Twitter and there is great jubilation among the family of the blog and the extended family."
The Paa star added: "I feel elated. It's like an intoxication and one that you can breathe through. So to all that who helped need to be rewarded by a remembrance ... thank you all."
The cinema icon is ahead of superstars like Shah Rukh Khan, who has 19.6 million followers, Salman Khan with 17.8 million, Aamir Khan with 17.6 million and Priyanka Chopra, who has 14 million followers, on Twitter.
Big B's upcoming movies are Te3N and Pink.