The Bayern Munich defender announced the shock news on Friday on the back of lifting the World Cup.
The 30-year-old captained his nation as the Germans overcame Argentina 1-0 in the final, making seven appearances to help them to their first major trophy since Euro 1996.
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Lahm will not play a role in Germany's hunt for more silverware, however, having told head coach Joachim Low that he's no longer available for the national team.
"I told Jogi Low about my decision to retire from international football on Monday," Lahm told Sport Bild. "I'd been thinking about it over the course of last season. I am delighted that things all came together with this World Cup win.
"I gave DFB president Wolfgang Niersbach a call this morning and thanked him and everybody else at the DFB for the last few years."
Lahm, who has captained Germany since permanently replacing Michael Ballack in 2011, made his official Germany debut in the 2-1 win over Croatia in February 2004 and had since developed into one of Germany's undisputed star players.
The right back has made 113 appearances for the freshly crowned world champion and sits fourth in the all-time rankings behind Lothar Matthaus (150 caps), Miroslav Klose (137) and Lukas Podolski (116).
Lahm featured at the European Championships of 2004, 2008 and 2012, as well as at the 2006, 2010 and 2014 World Cups.