Soldado was the joint top-scoring Spaniard in the Primera Division along with Fernando Llorente last season as his 17 goals helped guide Los Che to their third consecutive third-placed finish.
The former Real Madrid man also scored seven times in European competition as Valencia progressed to the Europa League semi-finals, but after scoring only once his last 10 games of the campaign Soldado was overlooked by Vicente del Bosque for the Spanish squad at the European Championships as his former club boss instead chose to take Llorente, Alvaro Negredo and Fernando Torres.
However, the 27-year-old's place as Valencia's main man has rarely been in doubt during his two-year stay at the Mestalla and his experience could become even more important next season with rookie manager Mauricio Pellegrino set to take over from Unai Emery.
Valencia president Manuel Llorente told the club's website: "Roberto's performance is fantastic as everyone has seen.
His application, desire to do the best for Valencia and winning mentality is a key part of this Valencia side and a reference for the Valencia support."