The shot stopper will leave the Camp Nou side at the end of the season, but will not get the chance to wave his fans farewell on the pitch due to a knee injury that has kept him out of action ever since March.
"The time has come for me to say goodbye to you all. Unfortunately, I wasn’t able to say goodbye playing football, as I would have liked, but that’s life at times, and this year has been a bit cruel to me in this regard," the letter reads.
"Thank you to Louis Van Gaal, for showing the courage necessary to gamble on a talent that only he could see. He began building this historic Barca side, which I have been privileged to be part of. My heartfelt thanks
"Thank you Frank Rijkaard, for giving me the confidence necessary, and allowing me to achieve glory, getting my hands on the European Cup in Paris. Wherever you are, I will be indebted to you for the rest of my life Mister.
"Thank you Pep, for having opened the door to playing a game that was unknown to me, for guiding me along the road where one has to keep looking for success, and we did it together, right? We’ll always have that Mister, and believe me, it will be eternal!.
"Thank you Tito! Wherever you are, I thank you for having taught us not only the way to keep winning as a team, but also the strength and character needed to face life.
"Thanks to all my colleagues with whom I’ve had the pleasure to work, that involves wearing the Barca crest on our chests day after day, for making me feel important within the group that we developed over all these years.
"And of course I cannot forget the most important people, over these 12 years as a professional, wearing this shirt, my most loyal fans."
Valdes has made over 500 official appearances for Barcelona since making his official debut in 2002-03.
