The actress, who garnered praise with her act as a pregnant woman on a mission to find her husband in the movie, also asked her fans and followers on Twitter to brace for "another mother of a story".
Vidya shared the news on Twitter with a 20-second video. Kahaani 2 is co-written and directed by Sujoy Ghosh.
The Paa star captioned the video: "Another mother of a story", which also is the tagline of the film.
Another mother of a story ..... pic.twitter.com/CNMmLhzeXL— vidya balan (@vidya_balan) May 9, 2016
The sequel, which went on the floors in March, also stars Arjun Rampal.
Kahaani revolved around a pregnant woman named Vidya Bagchi, who came to Kolkata from London in search of a man.
The 2012 film also featured Parambrata Chatterjee, Nawazuddin Siddiqui, Indraneil Sengupta, Dhritiman Chatterjee and Saswata Chatterjee.