The 28-year-old has decided to further his career abroad almost two years after arriving at the Estadio de Alvalade, where he became a key member of the team
The Spanish giants have splashed out €3.6 million to secure the services of the 28-year-old, but the deal could rise by €500,000 if the club hit certain targets in the Champions League.
Pereira, who moved to the Estadio de Alvalade in 2009 after two years at Sporting Braga, was an ever-present figure on the right side of the Leoes' defence.
"I am very happy to have signed for a big club such as Valencia and to join a league as competitive as the Spanish one," he told the club's official website.
The Portugal international, who is part of the Seleccao's 23-man squad for Euro 2012, will add some much-needed depth to Valencia's back line.
The move could spell the end of Los Che's interest in Ajax right-back Gregory van der Wiel, whose transfer to Mestalla failed to materialise in January despite having already agreed personal terms with the Spanish outfit.