Roy Krishna, David Williams, and Javi Hernandez scored for the Mariners, while SC East Bengal's solitary goal came in the form of a Tiri own goal.
Here are the player ratings for the Kolkata Derby:
ATK Mohun Bagan player ratings
Arindam Bhattacharya (8/10): Arindam Bhattacharya made some crucial saves and was dependable between the sticks for ATK Mohun Bagan.
Pritam Kotal (9/10): Pritam Kotal marked Bright Enobakhare brilliantly for the most part and was the defacto leader at the back for the Mariners.
Sandesh Jhingan (8/10): Sandesh Jhingan was on the heels of Anthony Pilkington throughout the game and didn't allow the Irishman to settle in the final third.
Tiri (8/10): The Spaniard had a mixed outing. His sublime long ball helped Roy Krishna break the deadlock, but he also scored an own goal while trying to clear a throw-in.
Subhasish Bose (8/10): Bose delivered several crosses from the left and won most of his duels with Ankit Mukherjee.
Carl McHugh (7/10): McHugh marked Matti Stienmann in midfield and came up on top against the German.
Lenny Rodrigues (6/10): Lenny Rodrigues struggled to contain the SC East Bengal midfielders and often required assistance from Carl McHugh.
Marcelinho (6/10): Marcelinho was not at his best and was substituted early due to an injury. He was marked meticulously by Daniel Fox.
Manvir Singh (6/10): Singh made some impressive runs down the right-flank and found Roy Krishna and David Williams with his pin-point crosses. But he was wasteful in front of goal.
Roy Krishna (9.5/10): Roy Krishna scored once and provided the assists for ATK Mohun Bagn's other two goals. The Fijian was in top form throughout the game and was rightly adjudged the Hero of the Match.
David Williams (8/10): Williams did not get much time on the ball but was incisive whenever he had possession. He scored the Mariners' second goal in the 72nd minute.
SC East Bengal player ratings
Subrata Paul (6/10): Subrata Paul made some quality saves, but looked sloppy at times between the sticks.
Sarthak Golui (5/10): Sarthak Golui lacked composure at the back. He gave the ball away too many times, thus putting SC East Bengal under pressure.
Raju Gaikwad (7/10): Raju Gaikwad was excellent with his long throw-ins. His deliveries troubled the ATK Mohun Bagan FC defenders, with Tiri scoring an own goal.
Daniel Fox (5/10): The Scottish centre-back was slow and couldn't keep up with the likes of Roy Krishna and David Williams. His sloppy pass was intercepted by Krishna, who set up Williams for ATK Mohun Bagan's second goal.
Narayan Das (7/10): Narayan Das was defensively resolute. He also delivered some quality balls from set-pieces and crosses.
Ankit Mukherjee (5/10): Ankit Mukherjee performed his defensive duties well, but his crosses were unsatisfactory.
Sourav Das (6/10): Sourav Das was overpowered by Carl McHugh in midfield and struggled to help SC East Bengal build attacks.
Anthony Pilkington (6/10): Anthony Pilkington put in a hard-working shift throughout the game but could not create openings for his side.
Matti Steinmann (6/10): Steinmann struggled to help SC East Bengal in attack and was forced to stay back and retrieve the ball for his side.
Jacques Maghoma (5/10): Maghoma cost SC East Bengal several potential counter-attacking moves by failing to release the ball quickly.
Bright Enobakhare (8/10): The Nigerian's solo runs and trickery kept the ATK Mohun Bagan defenders busy. His effort was SC East Bengal's only shot on target in the Kolkata Derby.