The former Manchester United winger has decided to hang up his boots at the age of 38, after playing for hometown club Estrela Amadora.
It ends a glittering career that also included spells in Turkey, Spain, Italy, Australia and the United States.
"The time has come to say goodbye," he said on social media. "I have decided to finish my career as a professional player.
"It's been an amazing ride and I wanted to thank every single person who has helped me and supported me, through the highs and lows during a career which lasted over 20 years, and gave me so many unforgettable memories.