The defender was named as the new Arsenal captain on Saturday.
Arsenal manager Arsene Wenger
The Gunners were in need of a new skipper this season after Mikel Arteta departed at the end of last season.
He had a number of candidates for the role, but he has elected to hand the German star the armband after he filled in as vice-captain for much of last season.
Arsenal's Per Mertesacker and Tottenham's Dele Alli in action
He is currently out injured so his role will have to initially be filled in by other players, but Wenger insists that it made perfect sense for him to be given the captaincy regardless.
“Per is a respected figure in the dressing room, is loved as well and is also a very demanding figure,” he told the club’s official website.
“I think it is absolutely natural to be him. [In his absence] that’s where it will be taken by the assistants. One of them will be Koscielny, also Cazorla – the experienced players.”
Sunderland's Jermain Defoe shoots wide under pressure from Arsenal's Per Mertesacker
It now remains to be seen if Mertesacker will prove to be a good appointment for Arsene Wenger.
There is no denying that he is well-liked at the club and choosing an experienced player is a smart move given the relative youthfulness of the current squad.
With him out injured for an extended period though, it will be interesting to see how the likes of Koscielny and Cazorla step up in his absence.
Arsenal's Laurent Koscielny and West Brom's Salomon Rondon in action