Newcastle United 1 Arsenal 2: Jamaal Lascelles forced out of fourth Premier League defeat
Goals from Granit Xhaka and Mesut Ozil gave Unai Emery's side a 2-1 win at St James's Park.
Newcastle had unsettled Arsenal before the break, but they gave away two goals early in the second half and weren't able to recover.
Substitute Ciaran Clark netted a late consolation goal for United, who remain 18th in the Premier League.
Fans had protested against owner Mike Ashley outside the stadium's club shop before the game.
There was no place for fit-again Jonjo Shelvey or out-of-form Kenedy in Rafa Benitez's starting XI. Benitez recalled Isaac Hayden to his team and fielded Joselu up front ahead of Salomon Rondon, who had returned late from international duty.
Rondon joined Shelvey and Kenedy on United's bench.
United quickly set about a nervy Arsenal side. They tried to get the ball in behind right-back Hector Bellerin at every opportunity.
A slip from Shkodran Mustafi let in Jacob Murphy, but he was bundled off the ball by Sokratis Papastathopoulos before he could get a shot away.
Federico Fernandez did well at the other end of the pitch to tackle Pierre-Emerick Aubameyang as he shaped up to shoot.
While Arsenal had had more of the ball, they hadn't looked comfortable, and the game looked there for the taking at the break, but the afternoon quickly unravelled in the second half.
Newcastle captain Jamaal Lascelles – who had twisted his ankle in the warm-up – was replaced by Clark.
Xhaka put Arsenal ahead with a 25-yard free-kick, conceded by Fernandez for a foul on Aubameyang. Ozil doubled their lead with a side-footed finish after a shot from Alexandre Lacazette was blocked.
Benitez was furious with his side's defending for the second goal.
United's manager replaced Murphy with Kenedy for the last 21 minutes. Yoshinori Muto was sent on late in the game, and Shelvey and Rondon had to stay on the bench.
Clark headed a late goal for Newcastle, who are without a win from their opening six league and cup games.
NEWCASTLE UNITED: Dubravka; Yedlin, Lascelles (Clark, 46), Fernandez, Dummett; Diame, Hayden; Ritchie (Muto, 79), Perez, Murphy (Kenedy, 69); Joselu. Subs not used: Darlow, Manquillo, Shelvey, Rondon.
ARSENAL: Cech, Bellerin, Mustafi, Sokratis, Monreal, Xhaka, Guendouzi, Ramsey, Ozil, Aubameyang (Mkhitaryan, 69), Lacazette. Subs not used: Leno, Elneny, Torreira, Lichtsteiner, Holding, Welbeck.
Goals: Xhaka 49, Ozil 57, Clark 90
Referee: Lee Probert (Gloucestershire)