The 29-year-old played 104 times for his country - scoring four goals - and made his final appearance from the substitutes' bench as Joachim Low's team won the World Cup with a 1-0 victory over Argentina.
The centre-back is now targeting the a first Champions League win for the Emirates Stadium outfit, as well as the Premier League title, following their FA Cup triumph in 2013-14.
"The main thing for me was that I wanted to be able to decide when my international career would end after ten years myself," he told Suddeutsche Zeitung.
"I now want to win the Premier League title with Arsenal and make an impact in the Champions League."
Mertesacker becomes the third member of the victorious Germany squad to walk away from the international game since their win in Rio de Janeiro, with captain Philipp Lahm and Miroslav Klose also calling time on their Die Mannschaft careers.
But Mertesacker believes the squad remains in good shape given the number of talented youngsters who remain at Low's disposal as they prepare for their Euro 2016 qualifying campaign.
"There is no reason to fear the future. Young players will come through. Germany are in better shape than ever before."
Mertesacker, along with international team-mates Mesus Ozil and Lukas Podolski, is set to sit out Arsenal's opening Premier League encounter against Crystal Palace on Saturday.