Gabriel Martinelli scored in Arsenal's win. Photo: Shaun Brooks
Gabriel, Gabriel Martinelli and captain Martin Odegaard all scored in the first half as the Gunners became the first team ever to win five consecutive away London derbies without conceding a goal in the English Football League.
Arsenal began the day with second-placed Manchester City hot on their heels after a 1-0 win over Crystal Palace pulled the reigning champions within two points.
With 11 games remaining, Mikel Arteta's side can stretch the gap to eight points with a home win against Crystal Palace next Sunday before City's next appointment in the Premier League.
"How does that sound? It's 11 finals for us, we take it game by game," said Leandro Trossard, who had a trio of assists as Arsenal took advantage of Fulham's porous defence at Craven Cottage.
"It's about keeping clean sheets as well. Today we did a great game; to keep it zero, you only need to score one. It was three, we're really happy with that."
Marco Silva's Fulham, who had lost only once in their previous seven home games in all competitions, are eighth in the league.
Gabriel, who also netted his debut goal against Fulham in 2020, put Arsenal on the scoreboard in the 21st minute with a header from inside a crowded six-yard box off Trossard's corner kick.
The Gunners had appeared to get on the board even earlier but Antonee Robinson's own goal was ruled offside by VAR.
Trossard teed up Martinelli in the 26th minute when his arching cross dropped at the far post for an easy header, the Brazilian's 12th goal of the season. Only four Premier League players have scored more.
Seconds before halftime, Odegaard took two touches to control Trossard's cross before smashing the ball past Fulham -- and former Arsenal -- keeper Bernd Leno.
Trossard, who was signed by Arsenal in January, said he had no negative feelings about not scoring.
"Really happy with it, I always try to help the team with goals and assists and help the team going forward," the Belgian said. "Today, it went my way and I'm just really happy that we won."
Brazilian Gabriel Jesus earned a roar from Gunners fans when he entered the game in the 77th minute, his first action since a knee injury suffered at the World Cup in November.
"It's a massive boost, he's been out for a while now and we know what he's going to give to the team again, and we're all excited to have him back," Odegaard said. "Very happy for him and for the team."
Jesus nearly scored in the 85th but his shot from close range went straight to the keeper.
Fulham found some life midway through the second half, with a couple of excellent scoring chances, including a header by Aleksandar Mitrovic that clanged off the crossbar.
-Reuters