Making his first league start since the season’s opening day, Oxlade-Chamberlain scored both goals in the second half to send Arsenal two points above Manchester City, who host third-place Chelsea on Monday.
The result got Arsene Wenger’s side back to winning ways after the 2-2 draw at Southampton that cost them top spot, while Palace were left one place above the relegation zone after a first defeat in three league games.
With Oxlade-Chamberlain in central midfield alongside Mikel Arteta, Arsenal quickly assumed control at the Emirates Stadium, but they struggled to make inroads against Tony Pulis’s well-drilled Palace.
The visitors had new goalkeeper Wayne Hennessey on the bench, but their current number one, Julian Speroni, seemed determined to stake a claim to the jersey.
He produced two excellent saves to thwart first Nacho Monreal and then Laurent Koscielny, before bravely diving at Bacary Sagna’s feet shortly before half-time.
It had been a disciplined and hard-working display from Palace, but two minutes into the second half they fell behind.
Former Arsenal striker Marouane Chamakh allowed Oxlade-Chamberlain to run into the box behind him and when the scheming Santi Cazorla picked out the England man with a dinked pass, he coolly lifted the ball over Speroni.
Arsenal goalkeeper Wojciech Szczesny was quickly called into action at the other end, saving a header from Cameron Jerome at point-blank range, but Oxlade-Chamberlain’s second goal in the 73rd minute settled the game.
The powerful 20-year-old, nicknamed ‘The Ox’, played a slick one-two with Olivier Giroud before cutting into the Palace box from the left and letting fly with a low drive that Speroni could not keep out.