Goals from Daniel Segovia (13th), Nishu Kumar (16th, 58th) and Sunil Chhetri (60th) gave Bengaluru a 4-0 win over Abahani Limited Dhaka.
Moments after Bengaluru's win, Aizawl came to their rescue by defeating New Radiant 2-1.
Bengaluru's previous visit to Dhaka had ended in defeat to the Bangladeshi side in the group stages of last year's AFC Cup campaign with late goals from Saad Uddin and Rubel Miya handing Albert Roca's men a 0-2 loss.
Bengaluru needed a win to qualify and were also relying on Aizawl FC to beat Maldives' New Radiant. Chetri led from the front as he assisted in three goals.
Chhetri then squirmed past two blue Abahani shirts to tee up Nishu who slammed the ball low to the corner and beyond Alam.
Chhetri then completed a hat-trick of assists when he chipped over the Abahani defence for Nishu to fantastically control the ball on his chest before firing home from close to make it 3-0.
Meanwhile, in Aizawl, where everyone who had anything to do with Bengaluru FC had their eyes on, Leonce Dodoz gave the hosts a 61st-minute lead that Romanian Andrei Ionescu doubled in the 82nd minute. New Radiant manager Oscar Bruzon's second substitution of Riham Abdul Ghanee with Ibrahim Atheeg Hassan in the 83rd minute proved fruitful as the latter reduced the margin with a lob over onrushing Aizawl goalkeeper Avilash Paul.
After having finished runners-up in the recently concluded Indian Super League season, Bengaluru FC walked into the AFC Cup 2018 as favourites and have exhibited a dominating display so far, winning five out of six matches with a solitary loss to top the Group E standings.
A draw process involving four zones - Central Asia, South Asia, East Asia and ASEAN - will determine BFC's next opponent.