The 22-year-old is set to sign a five-year deal with Valencia, subject to a medical.
Valencia president Manuel Llorente said: “He is a young player who has made a speedy progression but also has much experience at the highest level.
“We are happy to have him as part of the squad. I can reveal now that there was a long and secretive negotiation process but we have got the result that we wanted.
“Piatti is also from the province of Cordoba that has given us players such as (Mario) Kempes, Claudio Lopez and (Pablo) Aimar, so let’s hope this is a good sign.”
