The Gunners had won just one of their last seven opening-day fixtures and looked destined to start another campaign slowly as the 2015-16 champions took the lead twice only to lose 4-3.
The night started perfectly for Arsenal as new signing Alexandre Lacazette marked his league debut with a goal after just 94 seconds, only for Shinji Okazaki to cancel it out three minutes later.
Lacazette converted his first chance in the Premier League, heading home Mohamed Elneny’s inch-perfect cross to send the home fans into raptures.
But Arsenal’s defence, with essentially two full-backs playing in their back three, were soon caught out having been given a warning when want-away Leicester winger Riyad Mahrez volleyed wide.
Petr Cech was largely at fault, coming off his line but getting nowhere near Marc Albrighton’s deep cross as Foxes debutant Harry Maguire headed back across goal for Okazaki to nod in.
Sead Kolasinac forced Kasper Schmeichel into a smart save with a driven shot from just inside the box, but the Gunners again fell behind to Vardy’s strike as he tucked away Albrighton’s cross from close range.
Arsenal wanted a penalty for handball against Wilfred Ndidi with referee Mike Dean unmoved, but the equaliser came on the stroke of half-time after Sead Kolasinac unselfishly squared to Danny Welbeck with the goal gaping.
A Mahrez effort was tipped over by Cech as Leicester looked to regain their advantage, which they did from the resulting corner as Vardy, unmarked, headed home the Algerian’s set-piece.
Schmeichel was alert to prevent Hector Bellerin finishing off a slick Arsenal attack before Aaron Ramsey headed inches wide with his first touch. With time running out, Ramsey made sure he did not make the same mistake as he fired home from Xhaka’s pass with eight minutes remaining. There was a strong suspicion of handball by Mesut Ozil ahead of the corner that indirectly led to the goal.
Schmeichel’s brilliant diving stop denied Lacazette a fourth but, from the corner that followed, Giroud headed home off the underside of the crossbar.