Walcott scored his 19th goal of the season either side of strikes from Mesut Ozil and Olivier Giroud.
The victory has served to lift some of the doom and gloom mood that has engulfed their campaign.
Theo Walcott has revealed Arsenal beat West Ham to spare Arsene Wenger further criticism
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Fans have regularly protested against manager Arsene Wenger, whose long-term future at the club is uncertain.
But Walcott has revealed Arsenal thumped the Hammers in order to spare their manager from more criticism.
“Players will speak to each other, the manager will get his message across and then it’s up to us to do a job,” he told the club’s official website.
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Arsene Wenger's long-term future at Arsenal is in doubt
“We did that. We listened to what the manager had to say.
“He’s taken a lot of grief recently and we’ve just been in the background doing what we do. We’re the players that go out there very week and try to perform.
“It’s been a tough run, I can’t lie, but hopefully the win can push us on.”