Germany international Ozil signed for the Gunners from Real Madrid on transfer deadline day for a club-record fee of 47 million euros, having fallen out of favor at the Santiago Bernabeu.
The pair played together at Werder Bremen earlier in their careers and are teammates at international level.
And Mertesacker believes Ozil will adapt quickly to life in England, while helping the club challenge for trophies this season.
"I think that Arsene Wenger will get the best out of him," he said following Germany's 3-0 World Cup qualifying victory over Austria on Friday. "I think he will fit in.
"He suits us and we're really looking forward to playing with him and to be his teammate. We need players in every position - maybe two or three players, they can rotate and change position. We need to be dangerous up front and with him we are more dangerous."
Ozil could make his Premier League debut in Arsenal's trip to Sunderland on August 15 following the international break.