By David Brenchley
A Rachel Yankey strike and a sensational double from substitute Dan Carter in the second half saw the Gunners keep the pressure on the league leaders.
The first period was an even contest but Arsenal piled on the pressure after the interval and the inevitable came after just over an hour.
The ever impressive youngster Jordan Nobbs picked Yankey out on the left, who cut inside into the penalty area and fired past Carly Telford, who had put up a good fight in the previous 65 minutes.
Just 10 minutes later Carter doubled the hosts' lead after Kim Little's superb run took her past three defenders but her shot was blocked.
The ball broke to Carter, fully 25 yards out from goal, and her first time finish was sublime - and pretty much identical to her second.
With nine minutes remaining, Telford did well to punch a Yankey free kick clear but the ball fell straight to Carter, who unleashed her second long range strike of the evening.
The visitors boss Matt Beard was unhappy as his side had some good chances to put their London rivals on the backfoot early on in each half.
Chelsea's strikeforce were first into the action when a surging Claire Rafferty run down the left saw Kate Longhurst head against the post and Helen Lander's follow up effort blocked on the line after just five minutes.
Five minutes into the second period, they had yet another gilt-edged opportunity to break the deadlock but Arsenal keeper Emma Byrne made a good double save to deny Ashlee Hincks and former Gunner Helen Lander.
In between it was Arsenal doing all the running and Telford had to be on top form to keep them out. Julie Fleeting went close, with a shot on the turn that was straight at the former Leeds stopper.
Save of the game came on the half hour mark when left back Niamh Fahey marauded forward before unleashing a ferocious effort that was well parried out of danger by Telford.
After a disappointing first half, whatever Laura Harvey said at the break worked as her side came out firing on all cylinders and managed to wrap the game up with time to spare.
WSR will have all the reaction from both managers, Arsenal captain Katie Chapman and two-goal heroine Dan Carter tomorrow morning.
photos Janos Schmidt