Santi Cazorla and Aaron Ramsey, who both scored in the FA Cup triumph that ended Arsenals nine-year trophy drought in May, also netted against City with well-taken first-half strikes.
A makeshift City was a shadow of the team that won the Premier League for the second time in three years in May. And Olivier Giroud added to Citys discomfort by scoring with a dipping strike on the hour in the traditional curtain-raiser to the English season between the Premier League and FA Cup champions.
This gives us a positive platform to prepare, Arsenal manager Arsene Wenger said. Last year we were very consistent against the teams outside the top six and not consistent against the top six teams.
Arsenal, which finished fourth after leading for much of last season, opens against Crystal Palace on Saturday as it looks to win the Premier League for the first time since 2004.
Winning the Shield might set the tone for the opening weeks of the season, but is likely to be forgotten quickly. For David Moyes, it counted for nothing that his brief and unsuccessful Manchester United reign began by lifting the trophy here a year ago.
Given how Citys makeshift team performed in the first half, with just four of the players who started the title-clinching Premier League finale in May, it might be an uncomfortable start to the title defense at Newcastle on Sunday.
Perhaps most surprisingly, England goalkeeper Joe Hart was on the bench as new signing Willy Caballero was preferred in goal. But Hart, who was dropped during last season and successfully fought to regain his City place, saw the recruit from Malaga concede three times.
At the first match at Wembley since Englands pre-World Cup friendly against Peru in May, the shortage of Englishmen at top clubs was exposed again. With Hart dropped, Citys starting lineup lacked a single Englishman.
I dont see what nationalities the players are, Pellegrini said. I use the players who I think are the best players to win that game. It doesnt matter if they are England players.
Arsenal had a core of three, including new signing Calum Chambers who was assured in central defense.
Sanchezs lively debut
Arsenals trio of German World Cup winners Mesut Ozil, Per Mertesacker and Lukas Podolski are still on their post-Brazil break. But the cup winners, with $60 million-forward Alexis Sanchez making a lively full debut, were in control throughout against a City side that provided little threat.
Just like in the FA Cup final win against Hull, Cazorla scored Arsenals first goal. Jack Wilshere and Yaya Sanogo combined before the ball broke for Cazorla to strike low into the net in the 21st minute.
Sanogo dragged a shot wide and had a header collected by Caballero before helping ensure that Arsenals cushion was doubled before half time. Completing a swift break, the French forward held off Dedryck Boyata before passing for Ramsey to neatly stab the ball in the 42nd.
We passed the ball around very quickly and looked a threat every time, said Mikel Arteta, who has assumed the captaincy from Thomas Vermaelen after the defender joined Barcelona. Weve got pace up front now and it makes a big difference.
Although City appeared more effective at the start of the second half, with Stevan Jovetic denied by Arsenal goalkeeper Wojciech Szczesny, the deficit was extended on the hour when Giroud was given the space to send a dipping strike past Caballero.