The former AC Milan forward opened his account for the club after perfectly converting a 29th-minute penalty to hand his side the lead at the Stadio Branteo.
But Chievo levelled immediately after the break when striker Filip Dordevic netted in the 49th minute.
The Serbian forward then shot the visitors into the lead with a 64th minute strike.
Both sides were reduced to ten men, with Monza's Antonini Barilla sent off in the 43rd minute. Mattia Viviani was shown the marching orders with seven minutes left.
The defeat is Monza's first of the campaign since Kevin Prince Boateng joined in the summer transfer window from Fiorentina. Read Full Story