England opened the scoring after eight minutes in Nottingham, as the striker’s predatory instincts saw her rifle in from ten yards after the Arsenal defence failed to clear their lines.
The Gunners had chances to get back into the game, most notably through Vivianne Miedema, but a combination of resolute defending and wayward finishing saw the Blues hold out, until Williamson fired in with five minutes remaining.
And the game looked to be heading into extra-time, until England popped up at the back post with seconds remaining to claim the silverware for the Blues.
Chelsea wasted no time in exerting their dominance on the game, with Guro Reiten being denied by a smart stop from Manuela Zinsberger early on, as Sam Kerr’s pass carved open the Gunners’ defence.
They didn’t heed the warning as just a minute later the deadlock was broken when England continued her tremendous form in front of goal by netting the opener.
The striker pounced on a loose ball in the Arsenal penalty area to notch her 20th of the campaign, with Joe Montemurro’s side all at sea when defending a ball in from the Chelsea left.
Going behind sparked Arsenal into life, and Ann-Katrin Berger had to be on her toes to twice deny them an immediate equaliser, with the German thwarting Miedema’s header, before Jordan Nobbs was kept out.
After soaking up the pressure, the Blues could’ve made it two on the half-hour mark as England was left unmarked from a delivery into the penalty area, but this time her header failed to hit the target.
The action was relentless during the first stanza, with both sides putting on a show of the highest quality, albeit with a lack of end product, Caitlin Foord being another such culprit, with the Australian’s drive rippling the side netting minutes before the break.
The pace of the game showed no sign of slowing up after the interval, with Reiten the first to try her luck, before Arsenal began to turn the screw around the hour mark.
Miedema tried her luck twice within a matter of seconds, the first blocked, the second a whisker wide, before she saw a header back across goal go agonisingly past the post as the whole of the City Ground held its breath.
And even when the Dutchwoman did find the target, she was met by the brick wall that was Berger, with the shot-stopper pulling off some late heroics to smother the striker’s volley when she looked destined to score at the back post.
But the breakthrough finally came from the resulting corner, with Chelsea suffering from the same lack of ability to defend the set piece as for the first goal, when Leah Williamson smashed in from close range to seemingly send the game into extra time.
Both sides went all out to get the victory as the clock ticked down, and it was Chelsea who found the winner, as Kerr’s persistence on the right gave England the easiest of goals at the back stick to send her side into ecstasy.