The 33-year-old actress, who has delivered hits like 'Bajirao Mastani', 'Aitraaz' and 'Gunday' is ahead of actors Shah Rukh Khan's 1.2 million followers, Salman Khan's 3.5 million Instagram family and megastar Amitabh Bachchan, who has 1.3 million followers on the photo-sharing website.
"Whaaaa? 6 million already! So overwhelmed... Our family has grown so fast! Thank you for all the..." Priyanka tweeted on Wednesday night.
The actress, who is in the midst of shooting Hollywood film 'Baywatch', is very active on all her social media accounts. She constantly shares updates about her work and personal life.
On the Bollywood front, Priyanka was last seen in Prakash Jha's directorial 'Jai Gangaajal', in which she was seen playing a spunky police officer named Abha Mathur.
In Hollywood, she is debuting with 'Baywatch', in which she will be seen essaying a villain.
The 'Baywatch' movie based on the hugely popular 1990s TV series, also features Hollywood stars Dwayne Johnson and Zac Efron.