The France striker came off the bench and wrapped up the victory for Arsene Wenger's side, who had taken control of the game with goals from Santi Cazorla and Aaron Ramsey
Olivier Giroud all but confirmed victory for the Gunners in the second half with a dipping drive from distance which evaded new City goalkeeper Willy Caballero.
|VIEW FROM WEMBLEY
|By Greg Stobart
"The Community Shield is a match that matters more if you win it - and Arsenal supporters will feel optimistic that their team is ready for a genuine title challenge after this comprehensive victory.
"They came up against a very weak Manchester City side - particularly in defence - but the Gunners played with impressive speed and technique throughout the 90 minutes.
"Manuel Pellegrini will feel after this that he needs to re-integrate his World Cup stars as quickly as possible."
And Aaron Ramsey doubled the lead before half time, combining with Yaya Sanogo before displaying excellent skill to get beyond the defence and fire into the bottom corner.
City rallied for a brief spell after the break following the introduction of David Silva, but Giroud sealed the win shortly after the hour mark with his deflected effort.
Injuries and late returns from World Cup commitments combined to leave City without seven of the XI that sealed a second Premier League title in three seasons with a final-day win over West Ham in May, but Arsenal were also missing Per Mertesacker, Mesut Ozil and Lukas Podolski, who helped Germany triumph in Brazil.
It was Arsenal who acquitted themselves to far greater effect in the first half, as showpiece new signing Alexis Sanchez, Jack Wilshere, Aaron Ramsey and Santi Cazorla all buzzed inventively behind Yaya Sanogo to torment City's outgunned midfield and makeshift back four.
Cazorla and Ramsey's goals for a 2-0 advantage at half-time were the least Arsenal deserved and, although David Silva's introduction sparked an improvement from City, fellow substitute Olivier Giroud secured the win with an excellent long-range effort.
Arsenal dominated the opening exchanges but clear chances evaded them, and it required a last-ditch challenge from Mathieu Debuchy to prevent Samir Nasri from breaking the deadlock against his former club in the 14th minute.
That chance did nothing to turn the tide for the Premier League champions, for whom Yaya Toure and Fernando were being badly overrun in midfield and the opening goal stemmed from Arsenal exploiting generous amounts of space in front of City's back four.
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Sanogo dragged wide following Cazorla's searching ball in the 25th minute and Fernando lunged to block a drive from the Spain international as Arsenal continued to swarm forward.
Another debutant Arsenal defender, Calum Chambers, made a timely intervention to deny Nasri with the goal gaping on the end of Aleksandar Kolarov's 39th-minute cross, but Wenger's men grabbed a deserved second three minutes before the interval.
City were torn apart on the break and Ramsey collected Sanogo's pass, evaded Matija Nastasic with a cute touch and slotted home.
Sanchez had chances to extend the advantage in stoppage time and a ragged City backline were relieved to hear referee Michael Oliver's half-time whistle.
Silva's impact was instant as City resumed on the front foot and Stevan Jovetic headed against the post from Jesus Navas's 51st-minute centre before blazing the rebound off target.
Jovetic then received Kolarov's cutback to draw a sharp near-post stop from Wojciech Szczesny - the Arsenal goalkeeper's first save of note.
But Arsenal sealed victory in style after the hour, as substitute Giroud lashed a dipping 25-yard strike beyond Caballero's despairing dive, the recent signing from Malaga having been preferred to England's Joe Hart in Manuel Pellegrini's line-up.
City's performance will evoke uncomfortable memories of a pitiful title defence in 2012-13, although their launch of that campaign with a swaggering Community Shield win over Chelsea perhaps undermines this fixture as a useful form guide.
Arsenal, meanwhile, will hope this fine showing carries far more significance.