Alex Oxlade-Chamberlain's brilliant goal after 24 minutes settled a match played in warm sunshine.
The 21-year-old received a pass from Theo Walcott and cut inside Chelsea defender Cesar Azpilicueta before firing an unstoppable shot into the top corner of Thibaut Courtois' goal.
It was the first time in 14 attempts that Arsenal manager Arsene Wenger had got the better of Chelsea coach Jose Mourinho and the result offered hope to Chelsea's title rivals hat the champions might not have such an easy time this year.
