Kolkata went into the match leading 3-2 on aggregate from the first leg. Thus, a draw was enough for Jose Molina's side to reach the finals twice in three years.
Mumbai City FC, on the other hand, had to score at least one goal to take the match into extra time, a 2 goal win would have seen them qualify for the finals for the first time.
The match started with a bang as fans flocked the Mumbai Football Arena in numbers. Molina made a total of 9 changes in the starting XI from the first leg.
Kolkata's Robert Lalthlamuana was sent off early in the match after he received a double booking reducing them to 10 men for the next 47 minutes.
In the second half, Mumbai attacked in numbers as Alexandre Guimaraes deployed all his attacking option in the ground.
But the Kolkata defenders defended resolutely and kept the scoreline at bay for the team.
Drama unfolded as soon as the final whistle was blown. Kolkata's Juan Belencoso was involved in a tussle with Sena Ralte which instigated a huge fight among the players.
Here are some photos from the match:
Atletico de Kolkata and Mumbai City FC players
Atletico de Kolkata and Mumbai City FC players fighting after the match got over.
Atletico de Kolkata fans
Atletico de Kolkata fans celebrate their team's triumph.
ISL club owners and Nita Ambani
From left: Sourav Ganguly, Nita Ambani, Abhishek Bachchan, Ranbir Kapoor.
Atletico de Kolkata Vs Mumbai City FC
Atletico de Kolkata and Mumbai City FC players tussle for the ball.
Atletico de Kolkata players
Atletico de Kolkata players celebrate after the match.
All images are taken from ISL Twitter handle