"The last match at Euro 2015 was my last match for Germany," the 37-year-old Nowitzki told Bild newspaper.
On that occasion in Berlin on September 10, Germany lost 77-76 to Spain, a loss which knocked them out of the competition.
His retirement announcement came a few days after the International Basketball Federation announced that Germany had failed in a bid to stage one of the Olympic qualifying tournaments this year.
Nowitzki, a power forward who won an NBA title with the Mavericks in 2011, played 153 times for his country, making his debut in February 1997 and he amassed a points total of 3045.
He played in the German teams that took third place in the 2002 World Championships in the United States and second place in the 2005 European Championships in Serbia.
He was also the German flag carrier at the opening ceremony for the 2008 Olympics in Beijing.