GGF and PDP Construction are accused of running an elaborate scam involving €10 million ($13.61 million) worth of fake invoices in a hustle dreamt up by a known crook, the police said.
Their list of work includes the historic site of Florence's Hard Rock Cafe, Sting's 16th-century mansion in Chianti and the Uffizi, which houses paintings by masters such as Leonardo da Vinci.
The companies were registered under "clean" names but actually belonged to Giovanni Potenza, 62, who is linked to the Camorra crime syndicate and was found guilty in 2007 of mafia association, the reports said.
Police on Wednesday arrested six people in connection with the plot, and seized €11 million worth of assets including villas, luxury cars and bank accounts.
GGF and PDP relied on bogus companies in the region providing them with counterfeited invoices between 2007 and 2012 in exchange for a cut of the profits.