The award is the latest in a slew of accolades for Balan whose turn as the beautiful and tragic South Indian siren Silk Smitha has been widely and wildly praised.
The best actor honour went to Girish Kulkarni for "Deool" -- a Marathi film that shared the top prize for best feature film with "Byari", a movie in the Byari dialect spoken in parts of Karnataka.
Dirty Picture" also shared awards for make-up and costume design with the Marathi film "Balgandharva".
The Tamil-language "Azhagarsamiyin Kuthirai" was declared the best popular film while Gurvinder Singh won the best director prize for the Punjabi film "Anhe Ghorey Da Daan".
The feature film awards were announced by jury chairperson Rohini Hattangady at a news conference on Wednesday.
Among the honours that came Bollywood's way, "Chillar Party" walked away with three prizes: best original screenplay, best children's film and a shared award for best child artist -- with Partho Gupte also winning for "Stanley ka Dabba".
Shah Rukh Khan's "Ra.One" won the national award for best special effects.
"Game" picked up two of the three awards for audiography while "Zindagi Na Milegi Dobara" won the third. Bosco and Caesar bagged the choreography award for the ‘Senorita' song in "Zindagi Na Milegi Dobara".
Onir's "I Am" was adjudged the best Hindi film while Amitabh Bhattacharya won for the lyrics of the song "Agar zindagi" in "I Am".
The award for best film on social issues was shared by Ashvin Kumar for "Inshallah, Football" and Arun Chadha for "Mindscapes".
- Reports/UKAsian Staff
Vidya Balan wins Best Actress National Award for ‘The Dirty Picture’