When Alexis Sanchez put the ball in the net after four minutes, it was initially disallowed when Aaron Ramsey was adjudged to be interfering with play while offside.
Alexis Sanchez put Arsenal ahead after only five minutes at Wembley on Saturday and Chelsea were reduced to 10 men in the second half following Victor Moses' second yellow card.
It didn't hold Antonio Conte's men down as they drew level in the 77th minute when Diego Costa's effort deflected off Per Mertesacker and past David Ospina - although the Colombian global will feel he should have done better.
It was a great end to what has been a hard season for Wenger.More news: Trump makes G-7 deal on trade, takes rain check on climate
Goals from Sanchez and Aaron Ramsey either side of a Diego Costa strike secured the trophy for Arsene Wenger's side, as they deserved their win in a thoroughly enjoyable final.
The result means Arsene Wenger is the most successful manager in the competition's history with seven victories.
Arsenal scored again nearly immediately, through Aaron Ramsey, and Mertesacker ended up deservedly on the winning side.
Arsenal dominated the first half and could have doubled their advantage but Danny Welbeck struck the woodwork with a header and Ramsey chested the ball against the same post on the follow-up.
David Ospina denied Costa with a save off his face before Cahill was forced to clear off the line for the second time, as from the counter attack, Hector Bellerin fed Welbeck, who saw his deflected shot beat the Chelsea goalkeeper but not Cahill. The Gunners weren't expected to pose much difficulty for the Premier League champions.More news: Rain, thunderstorms in St. Lawrence County forecast through Friday
Arsenal won the FA Cup for the third time in four years on Saturday in a game where Chelsea were the strong favourites. The Welshman had also scored the winning goal in the 2014 cup final against Hull.
Many football fans were simply happy to see Chelsea finally lose after a storied season.
Giroud was played in behind with a nice pas, with the Frenchman then finding a ideal cross for Ramsey, whose late runs had caused Chelsea trouble all game.
The fan base certainly seems more divided, with Wenger bemoaning the "very hostile environment" created by some fans demanding his removal. It was their best display of the season.More news: Federal judge tosses out life sentences for DC sniper Malvo