The 31-year-old, a product of the club's youth academy who made his first-team debut in the 2002-03 campaign, announced last term he was quitting because the pressure of being Barca's first choice keeper for a decade had taken its toll.
He refused the offer of a contract extension beyond June 2014 and said he wanted to experience different cultures and different languages, prompting speculation he could accept a lucrative offer from big-spending Ligue 1 side Monaco.
Barca have made a solid start to the La Liga season under new coach Gerardo Martino and will be chasing a fifth win in five matches at Rayo Vallecano on Saturday (1800 GMT).
However, three of their four league wins have been by a single goal and Valdes has made a host of vital interventions that have helped avert an early setback to the club's bid for a fifth title in six years.
He was also decisive in Wednesday's Champions League Group H opener at home to Ajax Amsterdam, including stopping Kolbeinn Sigthorsson's 77th-minute penalty with a typically athletic dive.
Valdes has been praised by coach Gerardo Martino and team mates for his professionalism and his form has prompted calls for Spain coach Vicente del Bosque to give him the keepers' spot ahead of captain Iker Casillas.
"I would be very excited to win this Champions League and I want to win it in whatever manner possible," Valdes, who won the competition with Barca in 2006, 2009 and 2011, told reporters after the 4-0 success against the Dutch champions.
"I know that it will be the last one I compete in with Barca," he added.
"I am very grateful for the people's support. That gives me even more confidence."
Barca are the only team along with Atletico Madrid with a perfect 12 points from their four La Liga games.
Atletico, who started their Champions League campaign with a 3-1 win at home to Zenit St Petersburg, play at Real Valladolid on Saturday (2000) and will have combative forward Diego Costa back after he was suspended for the Zenit match.
Real Madrid host city rivals Getafe on Sunday (1700) fresh from knocking six goals past Galatasaray midweek and record signing Gareth Bale could make his second start after coming on as a second-half substitute in Istanbul.
The Wales winger, who became the world's most expensive player when Real bought him from Tottenham Hotspur for 100 million euros in the close season, scored on debut at Villarreal in last weekend's 2-2 draw.
Real coach Carlo Ancelotti was buoyed by the news on Wednesday that central defender Raphael Varane and fullback Fabio Coentrao trained with their team mates for the first time since being sidelined by injuries.
Getafe came from a goal down to stun Real 2-1 at their Coliseum stadium in the Madrid suburbs last season and midfielder Diego Castro said anything was possible at the Bernabeu on Sunday.
"You cannot fear anyone in football," Castro told a news conference on Wednesday. "Strange things often happen."
Real Sociedad need to pick themselves up for Saturday's match at home to Malaga (1400) after they fell 2-0 at home to Shakhtar Donetsk in their Champions League opener on Tuesday.