The 26-year-old's Barcelona contract expires at the end of the season, and neither party has shown signs of wanting to extend the deal.
His lack of opportunities in the Catalan first team has led him to address his future, and the Spaniard has revealed that he is in talks with the Portuguese club.
"I confirm there are advanced talks, but I cannot officially say yet that I will be a player of Benfica," Soriano told Maisfutebol.
"We have to wait. There is nothing signed yet and I am still under a contract with Barca."
Soriano has scored 57 goals in 81 appearances for Barcelona B since joining from Albacete in 2009.