Aishwarya plays Dalbir Kaur, the sister of Sarbjit Singh who died in a Pakistani jail.
The first look also includes a picture of actor Randeep Hooda, who plays the titular role.
While filming, Aishwarya met the real Dalbir Kaur, who campaigned relentlessly for her brother's release.
Sarbjit is being shot in and around Amritsar in Punjab.
Aishwarya shooting for Sarbjit. Love her look in this movie. Cannot wait for the release! pic.twitter.com/Ostmh8vHr5— S (@RandomMusings98) February 16, 2016
Randeep previously tweeted pictures of himself after his incredible make-under for the film - he lost 18 kilos in 28 days.
Actress Richa Chadha will play the role of Sarbjit's wife Sukhpreet in the film.
Directed by Omung Kumar, Sarbjit will release on May 19.