Panagiotis Kone and Manolo Gabbiadini also found the net to lift Stefano Pioli's side to 13th in the table on 21 points, five clear of the relegation zone. Chievo stay in 11th spot.
Kone's third goal of the season, a powerful header from the penalty spot after he lost his marker at a 13th minute corner, gave Bologna the lead their dominance deserved.
Chievo responded well, forcing Gyorgy Garics to head against his own post with 24 minutes gone.
Gilardino, though, doubled the hosts' lead with his first goal in seven games a minute before the break, ending a quick breakaway by clipping Chievo keeper Stefano Sorrentino.
The former Milan striker made it eight goals so far this season in the 59th minute when he pounced on more poor defending at a corner, tapping home from inside the six-yard box.
Gabbiadini completed the rout with a minute to go, powering past defender Marco Andreolli and slotting home.