In an evenly-contested battle, both the teams muffed several chances for a goalless first half.
The hosts regrouped after the break as Sanju Pradhan (76th), Tolgay Ozbey (77th) and Robin Singh (82nd) struck in succession to shoot them to second position with 48 points.
Sporting Clube de Goa stay at 37 points from 25 outings.
Leaders Dempo (54 points) have already won the title.
East Bengal began with Edmilson Marques Parrdal instead of in form striker Ozbey who started on the bench.
The red and gold came very close to take the lead in 31st minute but Edmilson's attempt off a corner was saved by Sporting custodian Ashok Singh.
The Brazilian was replaced by Ozbey in the 54th minute as the deadlock finally ended when man-of-the-match Sanju fired one in from outside the box in a solo effort.
The visitors defence was caught off guard when on a perfectly placed pass by Sanju found Ozbey who made no mistake to give a two-goal advantage.
East Bengal completed the rout when Ashok brought down Robin Singh inside the box as the Delhi lad slotted home from the spot.
The Trevor Morgan-coached side now have to win their last round battle against Air India in an away match on May 5 to finish runners-up. PTI TAP RG AT
