The 31-year-old midfielder's move is believed to be in the region of €1.5 million as per various sources.
Giaccherini was one of Italy's standout stars at Euro 2016 as they reached the quarter-finals before being dumped out on penalties by Germany. He got the azzurri off the mark at the tournament, scoring the first in a 2-0 victory over pre-tournament favourites Belgium and featured in every game.
Last term, Giaccherini spent time on loan with Bologna and impressed many with his performances. Napoli have beaten off a number of competitors to secure the signing of the former Juventus man including Chelsea and fellow Serie A clubs.
Speaking on the move to Napoli's official website, he said he "can’t wait" to play for an "important and prestigious club" in the partenopei and that running out at the San Paolo will be "fantastic."
Santon move edges closer to completion
Davide Santon is widely expected to complete a €6 million move from Inter to Napoli next week having been left out of the nerazzurri's US Tour squad. A five-year-contract is said have been agreed with a yearly salary of €1 million.
The full back, 25, only returned to Inter last year after a poor spell in England with Newcastle but with the arrivals of both Cristian Ansaldi and Caner Erkin, opportunities will be no doubt limited if he stayed at the San Siro next season.
Sunderland had came out as front runners and looked set to secure him before the move broke down over the players wage demands but now it appears that Napoli are on the verge of clinching the services of the eight time Italian international.