The veteran will say farewell to Germany fans on Monday for their Nations League clash with Holland.
In a letter published by BILD, Gundogan, 33, wrote: "I will travel to Munich for the match against the Netherlands with mixed feelings, because then I will realise once again that my DFB career is now finally over.
"The fact that the increasingly full schedule at club level also played a major role and that my body and mind were yearning for a few more breaks was one of the main factors in my decision."
"My years in the national team were certainly not as successful as my career in club football. But at the end of the day, I still played 82 international matches for my home country - a number that I would never have thought possible when I was a young man - a number that I am incredibly proud of!
"My proudest moment was certainly when I was able to lead our team as captain in the opening match of the European Championships at home. A team with which we finally managed to spark euphoria in the country again after so many difficult years."