Patrice Evra has described his Manchester United career as a "dream come true" after sealing a move to Juventus.
Evra will join the Italian champions on a two-year deal for a reported £1.2m after deciding the time was right for him to leave Old Trafford.
In a statement on the club's official website, the 33-year-old said United would always have a special place in his heart.
"After a great deal of thought I have decided the time is right for me to leave Manchester United. It is the biggest decision of my career as this club is, and will always remain, in my heart," he said.
"Joining and playing for Manchester United has been a privilege, a dream come true and my time here has been so memorable. Through the good times and the bad times we have all stuck together and remained loyal. I have always said you don't just join Manchester United, you join the family and long may that tradition continue."
The Frenchman ensured a difficult start to life at United after joining from Monaco in 2004. He was hauled off at half time in a 3-1 debut loss against arch rivals Manchester City.
But Evra soon established himself as United's first choice left back and was first choice full back during United's title winning campaign in 2006/07.
He became club captain in 2010, succeeding Rio Ferdinand, and went on to win a total of five Premier League titles, three League Cups and, on Evra's greatest night in a United shirt, a Champions League winners medal.
"An immense thank you to Sir Alex Ferguson for making it all possible, for giving me the privilege to be a captain, to be inspired by the legend of Manchester United and to understand that nobody is bigger than the club," he added.
"My biggest thanks go to the fans. We have had some fantastic times together, we lifted all of those trophies together and that night in Moscow will live with us all forever. Every single time I stepped out in that shirt I knew I was playing for the badge and for a very special club."
Evra signed a one-year extension to his United contract in May, but his postion as United's first choice left back was threatened after the signing of England international Luke Shaw.
The Frenchman's departure marks the end of an era for one of United's most successful backlines in the club's history after Nemanja Vidic and Rio Ferdinand also left the club.