Duff retires from Ireland duty
Duff, 33, informed Ireland coach Giovanni Trapattoni that he no longer wished to be considered for selection after a dismal UEFA Euro 2012 campaign that saw the Irish crash out at the group stage with three successive defeats.
The winger, who made his debut in 1998 against the Czech Republic, won 100 caps and captained Ireland in their last Euro 2012 group game against Italy.
Former Chelsea, Newcastle and Blackburn star Duff told www.fai.ie: "I found it very difficult to make this decision, not least for the respect in which I hold Giovanni Trapattoni.
"I have enjoyed so many good times in the green jersey and want to thank everyone involved, especially the fans for making the last 14 years so special.
"I want to wish Giovanni and everyone involved with the Irish team every success for the future and will be supporting them every step of the way."
Duff's retirement follows Ireland goalkeeper Shay Given's decision to quit international football earlier this month.
Trapattoni added: "Damien will be missed by us and by Irish fans everywhere. He was immensely skilful and a great example to the players who come after him. I give him my warmest best wishes for his future career."