The defender, who earned his 100th cap during the World Cup, says the national team is "in better shape than ever" heading into the future.
The 29-year-old surpassed the 100-cap mark during his country's triumphant World Cup campaign this summer, 10 years after making his senior debut.
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The towering center back says he is happy to bring an end to his international career on his own terms and insists the future of the Germany side has never looked brighter.
"The main thing for me was that I wanted to be able to decide when my international career would end after 10 years myself," he said. "There is no reason to fear the future. Young players will come through. Germany are in better shape than ever before. I now want to win the Premier League title with Arsenal and make an impact in the Champions League."
Mertesacker made his senior Germany debut under Jurgen Klinsmann in 2004, when he came on as a substitute against Iraq.
The former Werder Bremen stopper was part of the side that claimed third place at the 2006 and 2010 World Cups and finished runner-up to Spain at Euro 2008.
Mertesacker came on as a last-minute substitute in the 1-0 final victory over Argentina at the Maracana this summer, making six appearances during the tournament.