The experienced duo have been key figures in the Gunners' title challenge this season.
Mertesacker, 29, had entered the final 18-months of his contract, while Rosicky, 33, was yet to agree to extend beyond this summer when his current deal was set to expire.
However ahead of this weekend's FA Cup Sixth Round tie against Everton, the pair have penned their new contracts to remain at the Emirates Stadium for the foreseeable future.
Arsenal boss Arsene Wenger revealed his delight at securing the services of both Mertesacker and Rosicky.
“We are delighted that Mertesacker and Rosicky have committed their futures to the club," Wenger told the club's official website.
"They are players of exceptional quality and experience, and have consistently proven themselves at the highest level.
"There is a great feeling of togetherness and belief in the group and this news will only help to strengthen this further.”
