Giggs leaves Old Trafford as the most decorated man in their history having made a record 963 appearances, winning 13 Premier League titles, four FA Cup trophies and the Champions League twice.
In a statement on United’s website, the Welshman said he wanted to pursue a career in management.
He said: “After 29 seasons at Manchester United as a player and assistant manager, I know winning is in the DNA of this club – giving youth a chance, and playing attacking and exciting football. It’s healthy to have high expectations, it’s right to expect to win. Manchester United expects, deserves, nothing less.
“This is why it is a huge decision for me to step away from the club that has been my life since the age of 14. It has not been a decision that I have made lightly. I’ll take away so many special memories as well as a lifetime of experiences that will, I hope, serve me well in the future.