Mikel Arteta's side needed just 23 seconds to break the deadlock, Myles Lewis-Skelly slipping in Riccardo Calafiori, who slotted coolly past Gianluigi Donnarumma for one of the quickest goals in the fixture's long history.
Arsenal doubled their lead in the 28th minute when summer signing Christos Tzolis nodded Martin Odegaard's cross back across goal for Kai Havertz to head home. Three minutes into the second half, the Gunners were three up: Tzolis found Odegaard in the box, and the Norwegian sent Donnarumma to the ground with an outrageous fake shot before rolling the ball into the far corner.
The result gave Arsenal an 18th Community Shield title overall — moving them within three of record-holders Manchester United — and completed a perfect record against City specifically in this fixture, following earlier wins in 1934 (4-0) and 2014 (3-0), as well as the 2023 win on penalties after a 1-1 draw.
It was also a fifth Community Shield triumph for Arteta, who has now won all five of his appearances in the fixture, two as a player and three as Arsenal manager. City, missing Rodri to back surgery and new winger Ryan McAidoo to a shoulder injury, never recovered from their early setbacks and offered little going forward beyond a couple of half-chances for Antoine Semenyo, who twice tested David Raya late on, and a Bukayo Saka miss at the other end that summed up a comfortable afternoon for the champions.
Both of Arsenal's outfield goals were laid on by summer signings making their first Arsenal appearances in a competitive fixture. Bruno Guimaraes, signed from Newcastle United for a reported £75million, started in central midfield alongside Odegaard and Lewis-Skelly, while Christos Tzolis, a £39million buy from Belgian side Genk described by Arteta pre-match as a player who "takes the ball and has the goal between the eyes," set up Havertz's opener before turning provider again for Odegaard's clincher.
Arteta had also praised Guimaraes's efforts to force through his move from Newcastle, saying: "We had to do a lot of work to get a player out of a club like Newcastle. He was the captain there. I understand that it is always difficult, but he showed a real desire to come and join us."
For Maresca, the defeat capped a summer of major upheaval at the Etihad Stadium. City have overhauled their squad following Guardiola's departure, losing Bernardo Silva to Real Madrid, John Stones and Manuel Akanji as free-agent exits, Nathan Ake to Fenerbahce, goalkeeper James Trafford to Leeds United and, imminently, Tijjani Reijnders to Saudi side Al-Qadsiah.
The club's marquee summer arrival, midfielder Elliot Anderson, joined from Nottingham Forest for a reported British-record fee, and made his first appearance in City colours in the middle of the park, though he could not prevent a chastening opening act for the Italian.
Erling Haaland led the City line but was withdrawn quietly for Omar Marmoush as Maresca used the closing stages to manage fitness levels following his squad's exertions at the World Cup. The Italian rang the changes throughout the second half, with Nico Gonzalez replacing Mateo Kovacic and Jack Grealish, back at the club after a season on loan at Everton, introduced for a first appearance since his return.
Arsenal made just two changes of their own, with Declan Rice replacing goalscorer Bruno Guimaraes and Eberechi Eze coming on for the departing Odegaard, who picked up a late booking for a foul on Grealish. The match was played at Cardiff's Principality Stadium rather than the traditional Wembley setting, with Canadian singer The Weeknd's "After Hours til Dawn" tour occupying the national stadium.
Arsenal begin the defence of their Premier League title at home to newly promoted Coventry City on Friday, while City, still searching for their attacking identity under Maresca, open their campaign at Bournemouth two days later.
Line-ups:
Arsenal (4-3-3): David Raya; Ben White, Cristhian Mosquera, Gabriel Magalhaes, Riccardo Calafiori; Martin Odegaard (c), Bruno Guimaraes, Myles Lewis-Skelly; Noni Madueke, Kai Havertz, Christos Tzolis.
Substitutes: Kepa Arrizabalaga, Piero Hincapie, Martin Zubimendi, Mikel Merino, Declan Rice, Eberechi Eze, Max Dowman, Bukayo Saka, Viktor Gyokeres.
Manchester City (4-2-3-1): Gianluigi Donnarumma; Abdukodir Khusanov, Ruben Dias (c), Josko Gvardiol, Nico O'Reilly; Mateo Kovacic, Elliot Anderson; Antoine Semenyo, Phil Foden, Jeremy Doku; Erling Haaland.
Substitutes: Geronimo Rulli, Marc Guehi, Matheus Nunes, Rayan Ait-Nouri, Rico Lewis, Nico Gonzalez, Rayan Cherki, Jack Grealish, Omar Marmoush.
Substitutions:
Arsenal: Declan Rice for Bruno Guimaraes; Eberechi Eze for Martin Odegaard.
Manchester City: Omar Marmoush for Erling Haaland; Nico Gonzalez for Mateo Kovacic; Jack Grealish for Jeremy Doku.
Goals: Calafiori 1', Havertz 28', Odegaard 48'.
Booking: Odegaard (Arsenal).
Referee: Samuel Barrott.