"In the first half we gave Chelsea too much respect and distance. We were a bit scared to go for it," said Arsenal manager Arsene Wenger.
"We were not playing in the right position but we amended that in the second half and took control of the game."
The sides were meeting for the fifth time this season and it was clear that familiarity had bred a certain degree of contempt as the tackles flew in during a fiercely contested opening.
Arsenal had lost only one of their previous seven games against Chelsea, but were quickly under the cosh as Hazard put the visitors ahead, calmly stroking the ball past David Ospina after Chelsea carved open the hosts' backline.
The Emirates was subdued as Chelsea bossed the ball but a fortuitous leveller after 12 minutes brought the home crowd back to life and sparked Arsenal's revival.
A deep corner was met by Nacho Monreal whose header cannoned off the head of Marcos Alonso before ricocheting of Rudiger to leave Chelsea keeper Willy Caballero stranded.
Chelsea were hit with an injury blow when Willian was forced off with what looked like a hamstring problem after 29 minutes and his departure handed a debut off the bench to Ross Barkley.
That seemed to shift momentum in Arsenal's favour as the hosts finished the first half on the front foot, with Mesut Ozil seeing an effort deflected just wide, before they grabbed the lead shortly after the break.
Lacazette's pull back was deflected off Rudiger into the path of Xhaka, who stuck out a leg and poked the ball past Caballero from close range.
From that moment on Chelsea barely created a chance as Arsenal stayed resolute at the back and sharp on the counter, with the best opening falling to Alex Iwobi whose effort from 15 metres was saved by the legs of Caballero.
"There is a big disappointment ... there was great will to play at Wembley," Chelsea boss Antonio Conte said.
