Managerless Hull saw off Rotherham in convincing style to earn back-to-back wins for the first time this season.
Jacob Greaves bundled City ahead from close range, but Dan Barlaser crashed a shot in off the post from the corner of the 18-yard box to level in first-half stoppage-time.
Cyrus Christie's low drive beat Rotherham goalkeeper Viktor Johansson at his near post to restore the lead before Ryan Longman's close-range finish made it 3-1.
Ozan Tufan capped an impressive second half with Hull's fourth before Georgie Kelly converted Tom Eaves' low cross for a late consolation.
Having picked up just two points on the road before Wednesday's victory at Blackpool, an impressive display earned Hull a second away win in four days and Andy Dawson a third victory in six matches as interim manager.