On the Napoli website, De Laurentiis was pictured alongside Tonelli and the 26-year-old's freshly-signed contract, although Napoli did not reveal details of the deal.
A brief statement said: "Napoli have signed Lorenzo Tonelli on a permanent contract."
Tonelli's performances for Empoli this season initially earned him a call-up to a preliminary Italy squad for Euro 2016, although he was not included when coach Antonio Conte named a more definitive 30-man squad for the June 10-July 10 event on Monday.
Napoli finished the Serie A season nine points behind 32-times champions Juventus after a campaign that raised hopes of a first Scudetto in 26 years.
