The Cherries are understood to have agreed a loan fee of £720,000 with the Serie A club and the deal includes an option to buy the player for just over £3.5m, according to Sky Sports.
Both Bournemouth and Sunderland have expressed an interest in De Guzman this summer after being alerted to the former Swansea midfielder’s availability.
But it was understood that representatives of the Premier League newcomers were already heading to Italy for further talks with the 27-year-old, who joined Serie A side Napoli at the start of the 2014-15 season.
De Guzman starred at Swansea during two separate season-long loan spells from Villarreal between 2012 and 2014, making 95 appearances and scoring 15 goals for the Swans in all competitions.
The Dutchman started his career as a youth at Feyenoord before moving to Mallorca on a free transfer in 2010.
After a year at the Spanish club, De Guzman signed for Villarreal for £6m in 2011 and then moved to Napoli on a free last summer.