The 73-year-old megastar beaten his contemporaries Shah Rukh Khan (18.6 million), Aamir Khan (16.9 million), Salman Khan (16.8 million) and Priyanka Chopra (13.2 million) with his new milestone.
Bachchan's Twitter account became live in May, 2010 and ever since has been a one stop destination for his fans to connect, interact and engage with the actor.
"Baduuummmbaaaaa!! 20 MILLION ! Thank you all... Now to 30 million!! and your time starts NOW!!," he tweeted.
On Twitter, the "Wazir" actor is followed by stars like Mukesh Bhatt, Sridevi, Dilip Kumar, Madhuri Dixit among others. Bachchan has so far made over 48 thousand tweets.