"Visaranai was selected out of the 29 films that were in the race," Film Federation of India secretary general Supran Sen told PTI.
The crime-thriller, produced by actor-filmmaker Dhanush, is written and directed by Vetrimaaran. It is based on the novel Lock Up by M Chandrakumar.
Featuring Dinesh Ravi, Anandhi and Aadukalam Murugadoss, the film deals with police brutality, corruption, and loss of innocence in the face of injustice.
'Visaaranai #Anbum #amaithiyum malarathum ('Let love and peace bloom'),' Dinesh tweeted in Tamil.
The movie won three honours -- Best Feature Film in Tamil, Best Supporting Actor for Samuthirakani and Best Editing for Kishore Te -- at the 63rd National Film Awards.
The film premiered in the Orrizonti (Horizons) section of the 72nd Venice Film Festival, where it won the Amnesty International Italia Award.