Colombian forward Luis Muriel gave Fiorentina a fourth-minute lead with his third goal in two games since his move on loan from Sevilla.
Bottom-of-the-table Chievo thought they had levelled when Fiorentina goalkeeper Alban Lafont sent a goal kick straight to Emanuele Giaccherini, who fired into the net.
But the VAR ruled that the former Juventus and Sunderland forward had encroached when the kick was taken -- he had his foot inside the penalty area -- and disallowed the goal.
The Flying Donkeys then had a penalty appeal turned down and were still protesting when Marco Benassi scored a second for Fiorentina.
Mariusz Stepinksi headed one back for Chievo before halftime and Benassi turned villain on the hour when he blocked a goalbound shot with his arm on the line, was sent off and Sergio Pellissier, 39, levelled from the spot kick.
With the game going from one end to the other, Federico Chiesa broke clear to put Fiorentina ahead, then Chievo were awarded another penalty for handball by Gerson but this time Pellissier's effort was saved by Lafont.
Chiesa added a fourth and Filip Djordjevic headed one back but Chievo could not find an equaliser.
Fiorentina climbed to tenth in the standings with 30 points while Chievo remained on eight at the bottom.
(Writing by Brian Homewood; Editing by Christian Radnedge)
