The win sees Bashundhara replace their opponents as leaders of Group D by virtue of a better head-to-head record with both teams tied on seven points apiece, with Odisha FC one adrift.
Mohun Bagan started on the front foot and wrestled control of the game and after several wayward attempts, found the breakthrough in the 17th minute.
Subashish Bose played the perfect through ball for Jason Cummings down the left hand side, the Australian’s low cross was palmed by Bashundhara custodian Mehdi Srabon into the path of Liston Colaco, who gleefully tucked away the opener.
Bashundhara had a great opportunity to draw level in the 31st minute when Rakib Hossain’s cross found Miguel Ferreira at the far post but the Brazilian failed to get his shot on target.
However, Ferreira redeemed himself a minute before half-time, receiving a pass from Didier Brossou on the edge of the box, before turning to unleash a screamer right into the top corner to send both teams into the break on level terms.
After the interval, the momentum stayed with the home side as Robson da Silva worked himself an opening just inside the box, however, his curler hit the far post instead of the back of the net.
Then it was Hossain’s turn to force a save from Kaith, beating two Mohun Bagan players but sent his low shot direct at the keeper as Bashundhara heaped the pressure on the away side.
Sensing his team was in need of help,Mohun Bagan head coach Juan Ferrando replaced forward Armando Sadiku with midfielder Glan Martins, and it led to the Indian side producing their first shot at goal in the second half through Sahal Samad in the 68th minute.
But the respite was temporary as Bashundhara completed their comeback in the 80th minute, Hossain fed da Silva who picked his spot, calmly slotting the ball past an unsighted Kaith for the winner.