The 36-year-old former Italy international spent four seasons with the Azzurri but, as Liverpool keeper Reina prepares to begin a season on loan at the Stadio San Paolo, De Sanctis will now continue his career with Rudi Garcia's Roma.
After leaving Napoli's Dimaro training camp to fly to Rome's Fiumicino airport, he told La Repubblica Sport: "It's all agreed. I'm here to work hard and to have a great season.
"Have I spoken to the coach yet? Yes."
The former Udinese keeper is expected to undergo a medical at Trigoria this afternoon before replacing Maarten Stekelenburg in the Giallorossi goal following the Dutchman's departure for Fulham.