In a thrilling final round match, Gokulam Kerala edged Mohammedan Sporting 2-1 to be crowned champions.
Mohammedan are searching for their maiden title, while Gokulam Kerala are aiming to become the first team in the I-League era to defend their crown.
Even a draw will hand them the crown and make them the first club to defend the title in the 15-year-old league.
Andelo Rudovic had put Mohammedan ahead in the 27th minute.
Goals from Marcus Joseph, Faisal Ali, Brandon Vanlalremdika and Nikola Stojanovic made sure the Black Panthers quest for a third Durand title remained on course.
Friday's quarterfinal between Army Red and Bengaluru United was called off after an Army Red player tested positive for COVID-19.
Sarkar scored the winning penalty in the eighth minute. Mohammedans will take on Real Kashmir in the semifinals.
Real Kashmir pulled off a comeback 2-1 win against Peerless SC in Group B.