The 29-year-old had been on loan at Los Che from the Russian club but he has now agreed a contract that will see him stay at the side until the summer of 2015.
"I am happy to be staying at Valencia for two more years," he told the club’s official website.
"The clause in the contract took effect a while ago and now it's official that I belong to Valencia.
“I'm honored and proud to be here. I'm very happy because I'm officially a Valencia player in property (full ownership).”
Valdez has scored eight goals for Valencia so far this season in 31 matches.