The Newcastle United defender, who is now 32 years old, earnt his final cap after coming on in a penalty shoot-out defeat to England in Dusseldorf last month.
Schär posted an emotional message on his Instagram account waving goodbye and thanking his country for their support.
"After more than 10 years and 86 games for Switzerland, the time has come to say goodbye.
"I was able to represent my country in three World Cups and three European Championships. It filled me with great pride to appear on football pitches around the world with the Swiss Cross on my chest...
"I was able to experience incredibly beautiful moments with the Nati and the emotions I was able to experience will stay with me for the rest of my life.
"It's also time to say thank you: to my fellow players, the staff and coaches and of course to my family and the environment. Without you, this trip would not have been possible!
"Above all, I would like to thank the Swiss fans who have supported me over all these years. It meant the world to me and I will carry you in my heart."
Schär made his senior international debut against Brazil in August 2013 and has represented his country at every international tournament since.