Arsenal's captain, who is on his way back from a lengthy knee injury has signed a one-year contract extension as the Gunners look to tie down a host of stars.
Mertesacker joins french trio Olivier Giroud, Francis Coquelin and Laurent Koscielny in signing new deals while negotiations with Mesut Ozil and Alexis Sanchez continue to stall.
Manager Arsene Wenger was delighted to resign the defender, which he described as "an easy decision".
“He is a leader of the team and he is also one of the four centre backs who has experience and can guide the team,” Wenger said.
“There were no negotiations in fact, because he had an option for extension. So it’s not really a new contract, it’s just an extension of the old one. We had to take that option early in the season and the decision was made quite easily."
“On the pitch he has his own technical attributes, that is his reading of the game, his intelligence, his guidance. He’s good in the air because of his size.
“Mentally, he’s a guy who brings a level of urgency into the team, a level of focus, a level of desire to do well and he’s very demanding with the people around him. He’s very respected as well and that’s why he gets a lot from the players around him."